Methods and systems for frequency multiplexed communication in dense wireless environments

ABSTRACT

Systems, methods, and devices for high-efficiency wireless frequency division multiplexing are provided. A method includes exchanging, at an access point, at least one frame reserving a wireless medium with at least one of a first and second wireless device. The method further includes receiving a first communication on a first set of wireless frequencies from the first wireless device. The method further includes receiving a second communication, at least partially concurrent with the first communication, on a second set of wireless frequencies from the second wireless device. The method further includes transmitting at least one acknowledgment of the first and second communication. The first set and the second set are mutually exclusive subsets of a set of wireless frequencies available for use by both the first and second wireless device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/265,255, titled “METHODS AND SYSTEMS FOR FREQUENCY MULTIPLEXEDCOMMUNICATION IN DENSE WIRELESS ENVIRONMENTS,” filed Apr. 29, 2014,which claims the benefit of U.S. Provisional Application Nos.61/819,096, filed May 3, 2013, and 61/846,579, filed Jul. 15, 2013. Thecontent of these prior applications are considered part of thisapplication and are hereby incorporated by reference in their entirety.

FIELD

The present application relates generally to wireless communications,and more specifically to systems, methods, and devices for frequencymultiplexed wireless communication in dense wireless environments.

BACKGROUND

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks can be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks would be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN),wireless local area network (WLAN), or personal area network (PAN).Networks also differ according to the switching/routing technique usedto interconnect the various network nodes and devices (for example,circuit switching vs. packet switching), the type of physical mediaemployed for transmission (for example, wired vs. wireless), and the setof communication protocols used (for example, Internet protocol suite,SONET (Synchronous Optical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

However, multiple wireless networks may exist in the same building, innearby buildings, and/or in the same outdoor area. The prevalence ofmultiple wireless networks may cause interference, reduced throughput(for example, because each wireless network is operating in the samearea and/or spectrum), and/or prevent certain devices fromcommunicating. Thus, improved systems, methods, and devices forcommunicating when wireless networks are densely populated are desired.

SUMMARY

The systems, methods, and devices of the invention each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this invention as expressed bythe claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this invention provide advantages that include improvedcommunications between access points and stations in a wireless network.

One aspect of this disclosure provides a method of high-efficiencywireless frequency division multiplexing. The method includesdetermining, at an access point, a performance characteristic for eachwireless device in a set of wireless devices associated with the accesspoint. The method further includes categorizing each wireless device inthe set into at least a first and second subset of wireless devicesbased on the performance characteristic. The method further includesreceiving communications from the first subset of wireless devices on afirst set of wireless frequencies. The method further includes receivingcommunications from the second subset of wireless devices on a secondset of wireless frequencies, the second set of wireless frequenciesbeing a subset of the first. The first set of wireless devices have ahigher performance characteristic than the second set of wirelessdevices.

Another aspect provides an access point configured to performhigh-efficiency wireless frequency division multiplexing. The accesspoint includes a processor configured to determine a performancecharacteristic for each wireless device in a set of wireless devicesassociated with the access point. The processor is further configured tocategorize each wireless device in the set into at least a first andsecond subset of wireless devices based on the performancecharacteristic. The access point further includes a receiver configuredto receive communications from the first subset of wireless devices on afirst set of wireless frequencies. The receiver is further configured toreceive communications from the second subset of wireless devices on asecond set of wireless frequencies, the second set of wirelessfrequencies being a subset of the first. The first set of wirelessdevices have a higher performance characteristic than the second set ofwireless devices.

Another aspect provides an apparatus for high-efficiency wirelessfrequency division multiplexing. The apparatus includes means fordetermining, at an access point, a performance characteristic for eachwireless device in a set of wireless devices associated with the accesspoint. The apparatus further includes means for categorizing eachwireless device in the set into at least a first and second subset ofwireless devices based on the performance characteristic. The apparatusfurther includes means for receiving communications from the firstsubset of wireless devices on a first set of wireless frequencies. Theapparatus further includes means for receiving communications from thesecond subset of wireless devices on a second set of wirelessfrequencies, the second set of wireless frequencies being a subset ofthe first. The first set of wireless devices have a higher performancecharacteristic than the second set of wireless devices.

Another aspect provides a non-transitory computer-readable mediumincluding code that, when executed, causes an apparatus to determine, atan access point, a performance characteristic for each wireless devicein a set of wireless devices associated with the access point. Themedium further includes code that, when executed, causes the apparatusto categorize each wireless device in the set into at least a first andsecond subset of wireless devices based on the performancecharacteristic. The medium further includes code that, when executed,causes the apparatus to receive communications from the first subset ofwireless devices on a first set of wireless frequencies. The mediumfurther includes code that, when executed, causes the apparatus toreceive communications from the second subset of wireless devices on asecond set of wireless frequencies, the second set of wirelessfrequencies being a subset of the first. The first set of wirelessdevices have a higher performance characteristic than the second set ofwireless devices.

Another aspect provides a method of high-efficiency wireless frequencydivision multiplexing. The method includes receiving, at a firstwireless device, a reference signal from an associated access point, thereference signal indicative of a time of joint transmission with atleast a second wireless device. The method further includes transmittinga first communication to the access point based on the reference signal,the communication utilizing a first subset of wireless frequenciesavailable for use. The first communication is concurrent with a secondcommunication, from the second wireless device, utilizing a secondsubset of wireless frequencies, the second subset excluding the firstsubset.

Another aspect provides a first wireless device configured to performhigh-efficiency wireless frequency division multiplexing. The deviceincludes a receiver configured to receive a reference signal from anassociated access point, the reference signal indicative of a time ofjoint transmission with at least a second wireless device. The devicefurther includes a transmitter configured to transmit a firstcommunication to the access point based on the reference signal, thecommunication utilizing a first subset of wireless frequencies availablefor use. The first communication is concurrent with a secondcommunication, from the second wireless device, utilizing a secondsubset of wireless frequencies, the second subset excluding the firstsubset.

Another aspect provides an apparatus for high-efficiency wirelessfrequency division multiplexing. The apparatus includes means forreceiving, at a first wireless device, a reference signal from anassociated access point, the reference signal indicative of a time ofjoint transmission with at least a second wireless device. The apparatusfurther includes means for transmitting a first communication to theaccess point based on the reference signal, the communication utilizinga first subset of wireless frequencies available for use. The firstcommunication is concurrent with a second communication, from the secondwireless device, utilizing a second subset of wireless frequencies, thesecond subset excluding the first subset.

Another aspect provides non-transitory computer-readable mediumincluding code that, when executed, causes an apparatus to receive, at afirst wireless device, a reference signal from an associated accesspoint, the reference signal indicative of a time of joint transmissionwith at least a second wireless device. The medium further includes codethat, when executed, causes the apparatus to transmit a firstcommunication to the access point based on the reference signal, thecommunication utilizing a first subset of wireless frequencies availablefor use. The first communication is concurrent with a secondcommunication, from the second wireless device, utilizing a secondsubset of wireless frequencies, the second subset excluding the firstsubset.

Another aspect provides a method of high-efficiency wireless frequencydivision multiplexing. The method includes exchanging, at an accesspoint, at least one protection frame with at least one of a first andsecond wireless device. The method further includes receiving a firstcommunication on a first set of wireless frequencies from at least thefirst wireless device. The method further includes receiving a secondcommunication, at least partially concurrent with the firstcommunication, on a second set of wireless frequencies from the secondwireless device. The method further includes transmitting at least oneacknowledgment of the first and second communication. The first set andthe second set are mutually exclusive subsets of a set of wirelessfrequencies available for use by both the first and second wirelessdevice.

Another aspect provides an access point configured to performhigh-efficiency wireless frequency division multiplexing. The accesspoint includes a processor configured to exchange at least oneprotection frame with at least one of a first and second wirelessdevice. The access point further includes a receiving configured toreceive a first communication on a first set of wireless frequenciesfrom at least the first wireless device. The receiver is furtherconfigured to receive a second communication, at least partiallyconcurrent with the first communication, on a second set of wirelessfrequencies from the second wireless device. The access point furtherincludes a transmitter configured to transmit at least oneacknowledgment of the first and second communication. The first set andthe second set are mutually exclusive subsets of a set of wirelessfrequencies available for use by both the first and second wirelessdevice.

Another aspect provides an apparatus for high-efficiency wirelessfrequency division multiplexing. The apparatus includes means forexchanging, at an access point, at least one protection frame with atleast one of a first and second wireless device. The apparatus furtherincludes means for receiving a first communication on a first set ofwireless frequencies from at least the first wireless device. Theapparatus further includes means for receiving a second communication,at least partially concurrent with the first communication, on a secondset of wireless frequencies from the second wireless device. Theapparatus further includes means for transmitting at least oneacknowledgment of the first and second communication. The first set andthe second set are mutually exclusive subsets of a set of wirelessfrequencies available for use by both the first and second wirelessdevice.

Another aspect provides a non-transitory computer-readable mediumincluding code that, when executed, causes an apparatus to exchange, atan access point, at least one protection frame with at least one of afirst and second wireless device. The medium further includes code that,when executed, causes the apparatus to receive a first communication ona first set of wireless frequencies from at least the first wirelessdevice. The medium further includes code that, when executed, causes theapparatus to receive a second communication, at least partiallyconcurrent with the first communication, on a second set of wirelessfrequencies from the second wireless device. The medium further includescode that, when executed, causes the apparatus to transmit at least oneacknowledgment of the first and second communication. The first set andthe second set are mutually exclusive subsets of a set of wirelessfrequencies available for use by both the first and second wirelessdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary wireless communication system in which aspectsof the present disclosure can be employed.

FIG. 2A shows a wireless communication system in which multiple wirelesscommunication networks are present.

FIG. 2B shows another wireless communication system in which multiplewireless communication networks are present.

FIG. 3 shows frequency multiplexing techniques that can be employedwithin the wireless communication systems of FIGS. 1 and 2B.

FIG. 4 shows a functional block diagram of an exemplary wireless devicethat can be employed within the wireless communication systems of FIGS.1, 2B, and 3.

FIG. 5A shows the wireless communication system in which aspects of thepresent disclosure can be employed.

FIGS. 5B-5C show a timing diagram in which aspects of the presentdisclosure can be employed.

FIGS. 6A-6C show another timing diagram in which aspects of the presentdisclosure can be employed.

FIGS. 6D-6F show another timing diagram in which aspects of the presentdisclosure can be employed.

FIG. 7A shows an example reference signal that can be employed withinthe wireless communication systems of FIGS. 1, 2B, and 3.

FIG. 7B shows exemplary reference signal formats and fields that can beemployed within the wireless communication systems of FIGS. 1, 2B, and3.

FIG. 7C shows an example reference signal that can be employed withinthe wireless communication systems of FIGS. 1, 2B, and 3.

FIG. 8 shows another timing diagram in which aspects of the presentdisclosure can be employed.

FIGS. 9A-9D show additional timing diagrams in which aspects of thepresent disclosure can be employed.

FIG. 10 shows a flowchart for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 500 of FIG. 5.

FIG. 11 shows a flowchart for another exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 500 of FIG. 5.

FIG. 12 shows a flowchart for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 500 of FIG. 5.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to any specific structureor function presented throughout this disclosure. Rather, these aspectsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the disclosure to those skilled in theart. Based on the teachings herein one skilled in the art shouldappreciate that the scope of the disclosure is intended to cover anyaspect of the novel systems, apparatuses, and methods disclosed herein,whether implemented independently of, or combined with, any other aspectof the invention. For example, an apparatus can be implemented or amethod can be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein can be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Popular wireless network technologies may include various types ofwireless local area networks (WLANs). A WLAN can be used to interconnectnearby devices together, employing widely used networking protocols. Thevarious aspects described herein may apply to any communicationstandard, such as a wireless protocol.

In some aspects, wireless signals can be transmitted according to ahigh-efficiency 802.11 protocol using orthogonal frequency-divisionmultiplexing (OFDM), direct-sequence spread spectrum (DSSS)communications, a combination of OFDM and DSSS communications, or otherschemes. Implementations of the high-efficiency 802.11 protocol can beused for Internet access, sensors, metering, smart grid networks, orother wireless applications. Advantageously, aspects of certain devicesimplementing the high-efficiency 802.11 protocol using the techniquesdisclosed herein may include allowing for increased peer-to-peerservices (for example, Miracast, WiFi Direct Services, Social WiFi,etc.) in the same area, supporting increased per-user minimum throughputrequirements, supporting more users, providing improved outdoor coverageand robustness, and/or consuming less power than devices implementingother wireless protocols.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there can betwo types of devices: access points (“APs”) and clients (also referredto as stations, or “STAs”). In general, an AP may serve as a hub or basestation for the WLAN and an STA serves as a user of the WLAN. Forexample, an STA can be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, an STA connects to an AP viaa WiFi (for example, IEEE 802.11 protocol) compliant wireless link toobtain general connectivity to the Internet or to other wide areanetworks. In some implementations an STA may also be used as an AP.

An access point (“AP”) may also comprise, be implemented as, or known asa NodeB, Radio Network Controller (“RNC”), eNodeB, Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, orsome other terminology.

A station “STA” may also comprise, be implemented as, or known as anaccess terminal (“AT”), a subscriber station, a subscriber unit, amobile station, a remote station, a remote terminal, a user terminal, auser agent, a user device, user equipment, or some other terminology. Insome implementations an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein can beincorporated into a phone (for example, a cellular phone or smartphone),a computer (for example, a laptop), a portable communication device, aheadset, a portable computing device (for example, a personal dataassistant), an entertainment device (for example, a music or videodevice, or a satellite radio), a gaming device or system, a globalpositioning system device, or any other suitable device that isconfigured to communicate via a wireless medium.

As discussed above, certain of the devices described herein mayimplement a high-efficiency 802.11 standard, for example. Such devices,whether used as an STA or AP or other device, can be used for smartmetering or in a smart grid network. Such devices may provide sensorapplications or be used in home automation. The devices may instead orin addition be used in a healthcare context, for example for personalhealthcare. They may also be used for surveillance, to enableextended-range Internet connectivity (for example, for use withhotspots), or to implement machine-to-machine communications.

FIG. 1 shows an exemplary wireless communication system 100 in whichaspects of the present disclosure can be employed. The wirelesscommunication system 100 may operate pursuant to a wireless standard,for example a high-efficiency 802.11 standard. The wirelesscommunication system 100 may include an AP 104, which communicates withSTAs 106.

A variety of processes and methods can be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs 106.For example, signals can be sent and received between the AP 104 and theSTAs 106 in accordance with OFDM/OFDMA techniques. If this is the case,the wireless communication system 100 can be referred to as anOFDM/OFDMA system. Alternatively, signals can be sent and receivedbetween the AP 104 and the STAs 106 in accordance with code divisionmultiple access (CDMA) techniques. If this is the case, the wirelesscommunication system 100 can be referred to as a CDMA system.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106 can be referred to as a downlink (DL) 108,and a communication link that facilitates transmission from one or moreof the STAs 106 to the AP 104 can be referred to as an uplink (UL) 110.Alternatively, a downlink 108 can be referred to as a forward link or aforward channel, and an uplink 110 can be referred to as a reverse linkor a reverse channel.

The AP 104 may act as a base station and provide wireless communicationcoverage in a basic service area (BSA) 102. The AP 104 along with theSTAs 106 associated with the AP 104 and that use the AP 104 forcommunication can be referred to as a basic service set (BSS). It shouldbe noted that the wireless communication system 100 may not have acentral AP 104, but rather may function as a peer-to-peer networkbetween the STAs 106. Accordingly, the functions of the AP 104 describedherein may alternatively be performed by one or more of the STAs 106.

In some aspects, a STA 106 can be required to associate with the AP 104in order to send communications to and/or receive communications fromthe AP 104. In one aspect, information for associating is included in abroadcast by the AP 104. To receive such a broadcast, the STA 106 may,for example, perform a broad coverage search over a coverage region. Asearch may also be performed by the STA 106 by sweeping a coverageregion in a lighthouse fashion, for example. After receiving theinformation for associating, the STA 106 may transmit a referencesignal, such as an association probe or request, to the AP 104. In someaspects, the AP 104 may use backhaul services, for example, tocommunicate with a larger network, such as the Internet or a publicswitched telephone network (PSTN).

In an embodiment, the AP 104 includes an AP high-efficiency wirelesscomponent (HEWC) 154. The AP HEWC 154 may perform some or all of theoperations described herein to enable communications between the AP 104and the STAs 106 using the high-efficiency 802.11 protocol. Thefunctionality of some implementations of the AP HEWC 154 is described ingreater detail below with respect to FIGS. 2B, 3, 4, and 8.

Alternatively or in addition, the STAs 106 may include a STA HEWC 156.The STA HEWC 156 may perform some or all of the operations describedherein to enable communications between the STAs 106 and the AP 104using the high-frequency 802.11 protocol. The functionality of someimplementations of the STA HEWC 156 is described in greater detail belowwith respect to FIGS. 2B, 3, 4, 8B, and 10B.

In some circumstances, a BSA can be located near other BSAs. Forexample, FIG. 2A shows a wireless communication system 200 in whichmultiple wireless communication networks are present. As illustrated inFIG. 2A, BSAs 202A, 202B, and 202C can be physically located near eachother. Despite the close proximity of the BSAs 202A-202C, the APs204A-204C and/or STAs 206A-206H may each communicate using the samespectrum. Thus, if a device in the BSA 202C (for example, the AP 204C)is transmitting data, devices outside the BSA 202C (for example, APs204A-204B or STAs 206A-206F) may sense the communication on the medium.

Generally, wireless networks that use a regular 802.11 protocol (forexample, 802.11a, 802.11b, 802.11g, 802.11n, etc.) operate under acarrier sense multiple access (CSMA) mechanism for medium access.According to CSMA, devices sense the medium and only transmit when themedium is sensed to be idle. Thus, if the APs 204A-204C and/or STAs206A-206H are operating according to the CSMA mechanism and a device inthe BSA 202C (for example, the AP 204C) is transmitting data, then theAPs 204A-204B and/or STAs 206A-206F outside of the BSA 202C may nottransmit over the medium even though they are part of a different BSA.

FIG. 2A illustrates such a situation. As illustrated in FIG. 2A, AP 204Cis transmitting over the medium. The transmission is sensed by STA 206G,which is in the same BSA 202C as the AP 204C, and by STA 206A, which isin a different BSA than the AP 204C. While the transmission can beaddressed to the STA 206G and/or only STAs in the BSA 202C, STA 206Anonetheless may not be able to transmit or receive communications (forexample, to or from the AP 204A) until the AP 204C (and any otherdevice) is no longer transmitting on the medium. Although not shown, thesame may apply to STAs 206D-206F in the BSA 202B and/or STAs 206B-206Cin the BSA 202A as well (for example, if the transmission by the AP 204Cis stronger such that the other STAs can sense the transmission on themedium).

The use of the CSMA mechanism then creates inefficiencies because someAPs or STAs outside of a BSA can be able to transmit data withoutinterfering with a transmission made by an AP or STA in the BSA. As thenumber of active wireless devices continues to grow, the inefficienciescan begin to significantly affect network latency and throughput. Forexample, significant network latency issues may appear in apartmentbuildings, in which each apartment unit may include an access point andassociated stations. In fact, each apartment unit may include multipleaccess points, as a resident may own a wireless router, a video gameconsole with wireless media center capabilities, a television withwireless media center capabilities, a cell phone that can act like apersonal hot-spot, and/or the like. Correcting the inefficiencies of theCSMA mechanism may then be vital to avoid latency and throughput issuesand overall user dissatisfaction.

Such latency and throughput issues may not be confined to residentialareas. For example, multiple access points can be located in airports,subway stations, and/or other densely-populated public spaces.Currently, WiFi access can be offered in these public spaces, but for afee. If the inefficiencies created by the CSMA mechanism are notcorrected, then operators of the wireless networks may lose customers asthe fees and lower quality of service begin to outweigh any benefits.

Accordingly, the high-efficiency 802.11 protocol described herein mayallow for devices to operate under a modified mechanism that minimizesthese inefficiencies and increases network throughput. Such a mechanismis described below with respect to FIGS. 2B, 3, and 4. Additionalaspects of the high-efficiency 802.11 protocol are described below withrespect to FIGS. 5-13.

FIG. 2B shows a wireless communication system 250 in which multiplewireless communication networks are present. Unlike the wirelesscommunication system 200 of FIG. 2A, the wireless communication system250 may operate pursuant to the high-efficiency 802.11 standarddiscussed herein. The wireless communication system 250 may include anAP 254A, an AP 254B, and an AP 254C. The AP 254A may communicate withSTAs 256A-256C, the AP 254B may communicate with STAs 256D-256F, and theAP 254C may communicate with STAs 256G-256H.

A variety of processes and methods can be used for transmissions in thewireless communication system 250 between the APs 254A-254C and the STAs256A-256H. For example, signals can be sent and received between the APs254A-254C and the STAs 256A-256H in accordance with OFDM/OFDMAtechniques or CDMA techniques.

The AP 254A may act as a base station and provide wireless communicationcoverage in a BSA 252A. The AP 254B may act as a base station andprovide wireless communication coverage in a BSA 252B. The AP 254C mayact as a base station and provide wireless communication coverage in aBSA 252C. It should be noted that each BSA 252A, 252B, and/or 252C maynot have a central AP 254A, 254B, or 254C, but rather may allow forpeer-to-peer communications between one or more of the STAs 256A-256H.Accordingly, the functions of the AP 254A-254C described herein mayalternatively be performed by one or more of the STAs 256A-256H.

In an embodiment, the APs 254A-254C and/or STAs 256A-256H include ahigh-efficiency wireless component. As described herein, thehigh-efficiency wireless component may enable communications between theAPs and STAs using the high-efficiency 802.11 protocol. In particular,the high-efficiency wireless component may enable the APs 254A-254Cand/or STAs 256A-256H to use a modified mechanism that minimizes theinefficiencies of the CSMA mechanism (for example, enables concurrentcommunications over the medium in situations in which interference wouldnot occur). The high-efficiency wireless component is described ingreater detail below with respect to FIG. 4.

As illustrated in FIG. 2B, the BSAs 252A-252C are physically locatednear each other. When, for example, AP 254A and STA 256B arecommunicating with each other, the communication can be sensed by otherdevices in BSAs 252B-252C. However, the communication may only interferewith certain devices, such as STA 256F and/or STA 256G. Under CSMA, AP254B would not be allowed to communicate with STA 256E even though suchcommunication would not interfere with the communication between AP 254Aand STA 256B. Thus, the high-efficiency 802.11 protocol operates under amodified mechanism that differentiates between devices that cancommunicate concurrently and devices that cannot communicateconcurrently. In various embodiments used herein, “concurrently” canmean at least partially overlapping in time. Such classification ofdevices can be performed by the high-efficiency wireless component inthe APs 254A-254C and/or the STAs 256A-256H.

In an embodiment, the determination of whether a device can communicateconcurrently with other devices is based on a “location” of the device.For example, a STA that is located near an “edge” of the BSA can be in astate or condition such that the STA cannot communicate concurrentlywith other devices. As illustrated in FIG. 2B, STAs 206A, 206F, and 206Gcan be devices that are in a state or condition in which they cannotcommunicate concurrently with other devices. Likewise, a STA that islocated near the center of the BSA can be in a station or condition suchthat the STA can communicate concurrently with other devices. Asillustrated in FIG. 2B, STAs 206B, 206C, 206D, 206E, and 206H can bedevices that are in a state or condition in which they can communicateconcurrently with other devices. Note that the classification of devicesis not permanent. Devices may transition between being in a state orcondition such that they can communicate concurrently and being in astate or condition such that they cannot communicate concurrently (forexample, devices may change states or conditions when in motion, whenassociating with a new AP, when disassociating, etc.).

As used herein, a device can be classified as an “edge” device based ona physical location, a radio “location” (for example, a radio frequencycharacteristic), or a combination thereof. For example, in theillustrated embodiment, the STA 256B can be physically close to the AP254A. Accordingly, the STA 256B can be classified as an inner-celldevice (i.e., not an “edge” device) based on its physical proximity tothe AP 254A. Particularly, the STA 256B can be likely to successfullycommunicate with the AP 254A, even while the STA 256G is concurrentlytransmitting.

On the other hand, the STA 256C can be physically close to the AP 254A,but its antenna might be oriented poorly for communication with the AP254A. For example, it's the STA 256C could have a directional antennapointed at the STA 256G. Accordingly, although the STA 256C might bephysically close to the AP 254A, it can be classified as an edge devicedue to poor RF characteristics with respect to the AP 254A. In otherwords, the STA 256C might be unlikely to successfully communicate withthe AP 254A while the STA 256G is concurrently transmitting.

In another example, the STA 256A might be physically close to the AP254A, but it might also be physically close to the STA 256G. Due to theproximity between the STA 256A and the STA 256G, the STA 256A might beunlikely to successfully communicate with the AP 254A while the STA 256Gis concurrently transmitting. In this embodiment, the STA 256A mightalso be characterized as an edge device.

In various embodiments, RF characteristics that affect thecharacterization of a STA as an inner-cell device or a cell-edge devicecan include one or more of: a signal-to-interference-plus-noise ratio(SINR), an RF geometry, a received signal strength indicator (RSSI), amodulation and coding scheme (MCS) value, an interference level, asignal level, etc. In various embodiments, one or more physical and RFcharacteristics can be compared to one or more threshold levels. Thecomparisons can be weighted and/or combined. In various embodiments,devices can be determined to be in a condition such that they can orcannot communicate concurrently based on the solitary, weighted, and/orcombined physical and RF characteristics and associated thresholds.

Devices can be configured to behave differently based on whether theyare ones that are or are not in a state or condition to communicateconcurrently with other devices. For example, devices that are in astate or condition such that they can communicate concurrently (whichcan be referred to herein as “inner cell” devices) may communicatewithin the same spectrum. However, devices that are in a state orcondition such that they cannot communicate concurrently (which can bereferred to herein as “cell-edge” devices) may employ certaintechniques, such as spatial multiplexing or frequency domainmultiplexing, in order to communicate over the medium. The controllingof the behavior of the devices can be performed by the high-efficiencywireless component in the APs 254A-254C and/or the STAs 256A-256H.

In an embodiment, cell-edge devices use spatial multiplexing techniquesto communicate over the medium. For example, power and/or otherinformation can be embedded within the preamble of a packet transmittedby another device. A device in a state or condition such that the devicecannot communicate concurrently may analyze the preamble when the packetis sensed on the medium and decide whether or not to transmit based on aset of rules.

In another embodiment, cell-edge devices use frequency domainmultiplexing techniques to communicate over the medium. For example, inone embodiment, a first subset of cell-edge devices can communicateusing a first subset of available bandwidth. A second subset ofcell-edge devices can communicate using a second subset of availablebandwidth. Meanwhile, inner cell devices can communicate using anentirety of available bandwidth, or a third subset of availablebandwidth. In various embodiments, the third subset can be larger thanthe first and/or second subsets. In some embodiments, the third subsetcan intersect with the first and/or second subsets. In some embodiments,the third subset can include all available bandwidth (for example, allbandwidth licensed for use according to a specific technology such as802.11). Although channels, sub-channels, available bandwidth, andsubsets thereof, are generally depicted herein as contiguous, a personhaving ordinary skill in the art will appreciate that the terms usedherein can also encompass contiguous frequencies, interleavedfrequencies, sets of adjacent or non-adjacent tones with or withoutfrequency hopping, etc.

For example, with continuing reference to FIG. 2B, STAs 256A, 256C, and256G can be cell-edge devices, while STAs 256B and 256H can beinner-cell devices. Accordingly, in an embodiment, the STAs 256A and256C may form a first subset of cell-edge devices configured tocommunicate with the AP 254A on a first sub-channel (or set ofsub-channels). The first subset of cell-edge devices can be associatedwith a first BSA 252A. The STA 256G may form a second subset ofcell-edge devices configured to communicate with the AP 254C on a secondsub-channel (or set of sub-channels), which can be orthogonal to thefirst sub-channel. The second subset of cell-edge devices can beassociated with a second BSA 252C. Thus, in an embodiment, the STA 256Acan communicate at the same time (but on a different sub-channel) as theSTA 256G.

Meanwhile, the STA 256B may communicate with the AP 254A using a thirdsub-channel and the STA 256H can communicate with the AP 254C using thethird sub-channel. Thus, the STA 256B can communicate at the same time(and on at least some overlapping channels) as the STA 256H. Because theSTAs 256B and 256H are inner-cell devices, they are unlikely tointerfere with each other. In various embodiments, the STAs 256B and256H can also communicate on different overlapping or non-overlappingsub-channels.

In some embodiments, one or more devices in each BSA can coordinatefrequency use and re-use so as to reduce or minimize the chances ofinterference. For example, one or more devices in the first BSA 252A cantransmit an instruction to one or more devices in the first and/orsecond BSAs 252A and/or 252C, identifying sub-channels for use bycell-edge devices in one or both BSAs 252A and 252C. For example, the AP254A can instruct the STA 256A to use a specific sub-channel, and cansubsequently instruct the STA 256A to use another sub-channel. Likewise,the AP 254A can instruct the STA 256G to use a specific sub-channel, andcan subsequently instruct the STA 256G to use another sub-channel.

In another embodiment, cell-edge devices in the first BSA 252A cansimply start using a first sub-channel (or set of sub-channels). Forexample, the cell-edge devices in the first BSA 252A can choose a firstsub-channel based on one or more RF characteristics such as thesub-channel or set of sub-channels with the least interference. Thecell-edge devices in the second BSA 252C can observe the use of thefirst sub-channel and can choose a second sub-channel (or set ofsub-channels). For example, new interference on the first sub-channelmay cause the cell-edge devices in the second BSA 252C to choose thesecond sub-channel.

In some embodiments, frequency use and re-use can be uncoordinated. Forexample, the cell-edge devices can be configured to hop betweensub-channels on a scheduled, random, or pseudo-random basis. Thus, theSTA 256A can use a specific sub-channel for a first period of time, andcan subsequently use another sub-channel. Likewise, the STA 256G can usea specific sub-channel for a first period of time, and can subsequentlyuse another sub-channel. In some circumstances, the STAs 256A and 256Gmight hop to the same sub-channel by chance. However, they are alsolikely to occasionally transmit on different channels.

FIG. 3 shows frequency multiplexing techniques that can be employedwithin the wireless communication systems 100 of FIG. 1 and 250 of FIG.2B. As illustrated in FIG. 3, an AP 304A, 304B, 304C, and 304D can bepresent within a wireless communication system 300. Each of the APs304A, 304B, 304C, and 304D can be associated with a different BSA andinclude the high-efficiency wireless component described herein.

As an example, an available bandwidth of the communication medium can beset by a licensing body, a standards body, or preset or detected by adevice. For example, in an 802.11 standard, an available bandwidth canbe 80 MHz. Under a legacy 802.11 protocol, each of the APs 304A, 304B,304C, and 304D and the STAs associated with each respective AP attemptto communicate using the entire bandwidth, which can reduce throughput.In some instances, each respective AP may reserve the entire bandwidthwhile actually communicating only on a subset of available bandwidth.For example, a legacy channel can have a 20 MHz bandwidth. However,under the high-efficiency 802.11 protocol using frequency domainmultiplexing, the bandwidth can be divided into a plurality ofsub-channels. In the illustrated embodiment of FIG. 3, for example, the80 MHz available bandwidth is divided into four 20 MHz segments 308,310, 312, and 314 (for example, channels). The AP 304A can be associatedwith segment 308, the AP 304B can be associated with segment 310, the AP304C can be associated with segment 312, and the AP 304D can beassociated with segment 314. In various embodiments, other sizesub-channels can be used. For example, sub-channels can be between about1 MHz and 40 MHZ, between about 2 MHz and 10 MHz, and more particularlyabout 5 MHz. As discussed above, sub-channels can be contiguous ornon-contiguous (for example, interleaved).

In an embodiment, when the APs 304A-304D and the STAs that are in astate or condition such that the STAs can communicate concurrently withother devices (for example, STAs near the center of the BSA) arecommunicating with each other, then each AP 304A-304D and each of theseSTAs may communicate using a portion of or the entire 80 MHz medium.However, when the APs 304A-304D and the STAs that are in a state orcondition such that the STAs cannot communicate concurrently with otherdevices (for example, STAs near the edge of the BSA) are communicatingwith each other, then AP 304A and its STAs communicate using 20 MHzsegment 308, AP 304B and its STAs communicate using 20 MHz segment 310,AP 304C and its STAs communicate using 20 MHz segment 312, and AP 304Dand its STAs communicate using 20 MHz segment 314. Because the segments308, 310, 312, and 314 are different portions of the communicationmedium, a first transmission using a first segment would notinterference with a second transmission using a second segment.

Thus, APs and/or STAs, even those that are in a state or condition suchthat they cannot communicate concurrently with other devices, thatinclude the high-efficiency wireless component, can communicateconcurrently with other APs and STAs without interference. Accordingly,the throughput of the wireless communication system 300 can beincreased. In the case of apartment buildings or densely-populatedpublic spaces, APs and/or STAs that use the high-efficiency wirelesscomponent may experience reduced latency and increased networkthroughput even as the number of active wireless devices increases,thereby improving user experience.

FIG. 4 shows an exemplary functional block diagram of a wireless device402 that can be employed within the wireless communication systems 100,250, and/or 300 of FIGS. 1, 2B, and 3. The wireless device 402 is anexample of a device that can be configured to implement the variousmethods described herein. For example, the wireless device 402 maycomprise the AP 104, one of the STAs 106, one of the APs 254, one of theSTAs 256, and/or one of the APs 304.

The wireless device 402 may include a processor 404 which controlsoperation of the wireless device 402. The processor 404 may also bereferred to as a central processing unit (CPU). Memory 406, which mayinclude both read-only memory (ROM) and random access memory (RAM), mayprovide instructions and data to the processor 404. A portion of thememory 406 may also include non-volatile random access memory (NVRAM).The processor 404 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 406. Theinstructions in the memory 406 can be executable to implement themethods described herein.

The processor 404 may comprise or be a component of a processing systemimplemented with one or more processors. The one or more processors canbe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system may also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions mayinclude code (for example, in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 402 may also include a housing 408 that may includea transmitter 410 and/or a receiver 412 to allow transmission andreception of data between the wireless device 402 and a remote location.The transmitter 410 and receiver 412 can be combined into a transceiver414. An antenna 416 can be attached to the housing 408 and electricallycoupled to the transceiver 414. The wireless device 402 may also include(not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas.

The wireless device 402 may also include a signal detector 418 that canbe used in an effort to detect and quantify the level of signalsreceived by the transceiver 414. The signal detector 418 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 402 may alsoinclude a digital signal processor (DSP) 420 for use in processingsignals. The DSP 420 can be configured to generate a packet fortransmission. In some aspects, the packet may comprise a physical layerdata unit (PPDU).

The wireless device 402 may further comprise a user interface 422 insome aspects. The user interface 422 may comprise a keypad, amicrophone, a speaker, and/or a display. The user interface 422 mayinclude any element or component that conveys information to a user ofthe wireless device 402 and/or receives input from the user.

The wireless devices 402 may further comprise a high-efficiency wirelesscomponent 424 in some aspects. The high-efficiency wireless component424 may include a classifier unit 428 and a transmit control unit 430.As described herein, the high-efficiency wireless component 424 mayenable APs and/or STAs to use a modified mechanism that minimizes theinefficiencies of the CSMA mechanism (for example, enables concurrentcommunications over the medium in situations in which interference wouldnot occur).

The modified mechanism can be implemented by the classifier unit 428 andthe transmit control unit 430. In an embodiment, the classifier unit 428determines which devices are in a state or condition such that they cancommunicate concurrently with other devices and which devices are in astate or condition such that they cannot communicate concurrently withother devices. In an embodiment, the transmit control unit 430 controlsthe behavior of devices. For example, the transmit control unit 430 mayallow certain devices to transmit concurrently on the same medium andallow other devices to transmit using a spatial multiplexing orfrequency domain multiplexing technique. The transmit control unit 430may control the behavior of devices based on the determinations made bythe classifier unit 428.

The various components of the wireless device 402 can be coupledtogether by a bus system 426. The bus system 426 may include a data bus,for example, as well as a power bus, a control signal bus, and a statussignal bus in addition to the data bus. Those of skill in the art willappreciate the components of the wireless device 402 can be coupledtogether or accept or provide inputs to each other using some othermechanism.

Although a number of separate components are illustrated in FIG. 4,those of skill in the art will recognize that one or more of thecomponents can be combined or commonly implemented. For example, theprocessor 404 can be used to implement not only the functionalitydescribed above with respect to the processor 404, but also to implementthe functionality described above with respect to the signal detector418 and/or the DSP 420. Further, each of the components illustrated inFIG. 4 can be implemented using a plurality of separate elements.

The wireless device 402 may comprise an AP 104, a STA 106, an AP 254, aSTA 256, and/or an AP 304, and can be used to transmit and/or receivecommunications. That is, either the AP 104, STA 106, AP 254, STA 256, orAP 304 may serve as transmitter or receiver devices. Certain aspectscontemplate signal detector 418 being used by software running on memory406 and processor 404 to detect the presence of a transmitter orreceiver.

FIG. 5A shows the wireless communication system 500 in which aspects ofthe present disclosure can be employed. As illustrated in FIG. 5A, thewireless communication system 500 includes a BSA 502. The BSA 502 mayinclude the AP 504 and STAs 506A-506E. In an embodiment, the AP 504 andthe STAs 506A-506D each include the high-efficiency wireless componentdiscussed above. However, the STA 506E does not include thehigh-efficiency wireless component. Thus, STAs 506A-506D are referred toas high-efficiency STAs, whereas STA 506E is referred to as a legacy STA(for example, because it is compatible with regular IEEE 802.11protocols, such as IEEE 802.11n, IEEE 802.11ac, etc.).

In some embodiments, the legacy STA 506E would reserve an entireavailable bandwidth (for example, 80 MHz) while transmitting to a legacyAP (which does not include the high-efficiency wireless component) via alegacy channel (for example, 20 MHz). In an embodiment, thehigh-efficiency AP 504 can be configured to receive data on multiplesub-channels simultaneously. For example, the STA 506A can transmit tothe AP 504 via uplink (UL) communication 510, the STA 506B can transmitto the AP 504 via uplink (UL) communication 512, and the STA 506C cantransmit to the AP 504 via uplink (UL) communication 514 at the sametime as the STA 506E transmits to the AP 504 via uplink (UL)communication 518. In the illustrated embodiment, the UL communication518 can be a legacy channel communication, and the UL communications510, 512, and 514 can be high-efficiency channel communicationsoccupying unused available sub-channels. In an embodiment, the STA 506Dcan also transmit to the AP 504 via UL communication 516. As illustratedin FIG. 5A, STAs 506A-506C can be located closer to the AP 504 than STAs506D-506E. The UL communications 510, 512, 514, 516, and 518 can be madeby the AP 504 according to the uplink frequency domain multiplexing (ULFDM) protocol described herein.

An UL FDM protocol may include three data exchange stages: (1) datatransmission; (2) protection; and (3) acknowledgment. The protectionstage may precede the data transmission stage and the acknowledgmentstage may follow the data transmission stage. In the protection stage,techniques can be employed to prevent interference. In the datatransmission stage, data one or more STAs may transmit data to the AP.In the acknowledgment stage, the STAs may confirm that the AP receivedthe appropriate data. Each of these stages may occur concurrently ondifferent channels according to the frequency domain multiplexingprinciples discussed herein. In addition, the UL FDM protocol mayinclude rules related to the timing of the start of transmissions by theSTAs 306A-306E (FIG. 3).

Data Transmission Stage

During the UL data transmission stage, data is transmittedsimultaneously by multiple STAs on different channels. The STAs cantransmit on any channel discussed herein, particularly those within theavailable bandwidth. In an embodiment, several data transmission optionsare available during the data transmission stage. In particular, severaloptions are available for allocating STAs on different channels suchthat the STAs can communicate concurrently. These options may also allowfor both legacy STAs and high-efficiency STAs to communicateconcurrently. Thus, the techniques described herein to improve networkthroughput and reduce latency can be implemented in devices that arecompatible with high-efficiency STAs and that are backwards compatiblewith existing legacy STAs.

For example, an existing PHY layer of the regular IEEE 802.11 protocol(for example, the 802.11n, 802.11ac, etc.) can be coupled with a newmedia access control (MAC) mechanism to allocate STAs on differentchannels. As another example, a new PHY layer preamble can be createdfor the high-efficiency 802.11 protocol and be used by STAs on differentchannels. As another example, the existing PHY layer of the regular IEEE802.11 protocol and the new PHY layer preamble can be used by STAs totransmit STAs on different channels simultaneously or essentiallysimultaneously.

FIGS. 5B-5C show a timing diagram in which aspects of the presentdisclosure can be employed. In particular, FIGS. 5B-5C show a timingdiagram that can be used in accordance with the existing PHY layer ofthe regular IEEE 802.11 protocol and the new MAC mechanism. Asillustrated in FIGS. 5B-5C, four channels are present: channel 520,channel 522, channel 524, and channel 526. As discussed above, the termchannel used herein can refer to any of a contiguous portion of spectrumor a set of non-adjacent intervals of spectrum, in which case the termbandwidth for the channel can refer to the sum of the bandwidth of eachinterval. As used herein, channel 526 is referred to as a primarychannel (for example, a default channel used by STAs operating on theregular IEEE 802.11 protocol) and channels 520, 522, and 524 arereferred to as secondary channels. In some embodiments, legacy STAs canonly transmit on secondary channels in combination with transmission onthe primary channel. In contrast, in various embodiments, HEW STAs cantransmit packets on the primary channel, on the primary channel incombination with secondary channels, or on secondary channels withoutincluding the primary channel. The channels 520, 522, 524, and 526 canbe contiguous (for example, each channel 520, 522, 524, and 526 coversconsecutive 20 MHz frequency ranges, such as from 1000 MHz to 1080 MHz)or non-contiguous (for example, there are gaps in frequency between oneor more of the channels 520, 522, 524, and/or 526).

In one embodiment all transmissions come from HEW STAs. In anotherembodiment, one transmission comes from a legacy STA, and one or moreother transmissions come from one or more HEW STAs. In variousembodiments, the transmission bandwidth of each STA can be same or canbe different. In various embodiments, exemplary bandwidths used by eachSTA can include one or more of 2.5 MHz, 5 MHz, 7.5 MHz, 10 MHz, 15 MHz,20 MHz, 30 MHz, 40 MHz, 60 MHz, and 80 MHz. In some embodiments,transmissions from all the STAs can be allocated such that notransmissions are on adjacent channels.

In an embodiment, the primary channel (alone or in combination withadditional secondary channels, for example in legacy 11n/11ac operation)is used for communications from legacy STAs (for example, STA 506E) tothe AP 504. Secondary channels are also used for communications fromhigh-efficiency STAs (for example, STAs 506A-506D) to the AP 504.

In various embodiments, duration of the transmission from multiple STAscan be same or different. Different amounts of data and different datarate used for the transmission can result in a different time for thetransmission of each data. In certain cases, it is advantageous that allthe transmissions end at the same time, irrespective of the differentminimum times that would be used by each STA to send the data. In suchcases where all the transmissions end at the same time, each STA caninclude one or more additional padding bytes to the frame, so that theframe length matches a target frame length. The target duration can beindicated in a frame received immediately before the transmission (forexample, the reference signals CTX described below with respect to FIGS.6A-6C), and/or can be previously negotiated or indicated by the AP. Invarious embodiments, the padding operation can be performed by addingone or more aggregated media access control protocol data unit (A-MPDU)sub-frames and/or padding bytes, for example as defined in the IEEE802.11ac standard.

In an embodiment, the AP 504 transmits, and the STAs 506A-506E receive,a MAC message that associates the STAs 506A-506E with channels, therebyindicating which channel the AP 504 plans to use to communicate orreceive a communication with a respective STA 506A-506E. In someembodiments, the AP 504 defaults to communicating with the STA 506E onthe primary channel since the STA 506E is a legacy STA. Similarly, theSTA 506E can default to the primary channel for transmissions to the AP504. Thus, the AP 504 may not transmit the MAC message to the STA 506E.Rather, the AP 504 may transmit the MAC message only to thehigh-efficiency STAs 506A-506D. In other embodiments, the AP 504transmits the MAC message to each STA 506A-506E. In various embodiments,the MAC message can include one or more management frames sent from theAP 504 to the STAs 506A-506D, and can include an indication of theallocated channel for each STA (either explicitly or implicitly such asbased on a categorization). In some embodiments, the MAC message isreferred to as a reference signal, described in greater detail belowwith respect to FIG. 7A.

Channel Access

In various embodiments, it can be beneficial to synchronize the start oftransmission by the STAs 506A-506E. For example, it can be easier todecode the transmissions when they start at the same time. Because theSTAs 506A-506E are disparate devices, however, it can be challenging tocoordinate a synchronized transmission time. In various embodiments,transmission can be synchronized based on a solicited or unsolicitedreference signal from the AP 504. In other embodiments, transmission canbe synchronized based on a schedule set by the AP 504 and/or STAs506A-506E.

FIGS. 6A-6C show another timing diagram in which aspects of the presentdisclosure can be employed. As described above, the primary channel (forexample, channel 526) and/or one or more of the secondary channels (forexample, channels 520, 522, and/or 524) can be used for transmissions bylegacy STAs and the primary channel and/or secondary channels can beused for transmissions by high-efficiency STAs. The channels 520, 522,524, and/or 526 may or may not be contiguous. In an embodiment, the AP504 can transmit one or more unsolicited reference signals CTX 601-604to the STAs 506A-506E. The reference signals CTX 601-604 can indicatethat STAs with data to send should begin transmitting upon receipt (orat a predetermined synchronization point after receipt). Thesynchronization point can be at, for example, a short inter-frame space(SIFS), a point coordination function (PCF) inter-frame space (PIFS), oranother predefined time after the end of reception of the CTX frame. Inan embodiment, the STAs 506A-506E receive the reference signal CTX601-604 can begin to transmit the communications 510, 512, 514, and 518.The reference signals CTX 601-604 are described in greater detail hereinwith respect to FIG. 7A. In various embodiments, the synchronizationpoint can be referred to as a time of joint transmission.

As shown in FIG. 6A, the AP 504 can transmit the reference signal CTX601-602 on a plurality of sub-channels, or even all sub-channels. InFIG. 6A, the STAs 506A-506E are only able to receive on their assignedchannel. Accordingly, the AP 504 transmits the reference signal CTX601-604 on all channels. In some embodiments, each CTXs can contain sameinformation. In some embodiments, various CTXs can contain differentinformation on each channel. In some embodiments, the STAs 506A-506E canreceive the reference signal on any channel. Accordingly, as shown inFIG. 6B, the AP 504 may transmit a single reference signal CTX 602 onany sub-channel that can be received by the STAs 506A-506E, for example,on the primary channel.

The embodiment shown in FIG. 6C, the legacy STA 506E can only receivethe reference signal CTX 601 on the primary channel 526. However, theHEW STAs 506A-506C are able to receive the reference signal CTX 601 onany channel. Accordingly, the AP 504 transmits the reference signal CTX601 on the primary channel 526. In various embodiments, othercombinations of STA capability are possible.

In general, the AP 504 can be configured to transmit the referencesignals CTX 601-604 on a minimum number of sub-channels in order tonotify all target STAs. 506A-506E. In some embodiments, where more thanone sub-channel will suffice, the AP 504 may transmit a reference signalCTX 601 on the sub-channel with the least interference, or may transmitone or more redundant reference signals CTX 601-604. The referencesignals CTX 601-604 sent on multiple sub-channels can be exactly same,or can be different per sub-channel.

In an embodiment, a random back-off counter can be associated with a CTXtransmission channel (such as the primary channel 526 in FIG. 6C), asdefined by the enhanced distributed channel access (EDCA) procedure ofIEEE 802.11. When the random back-off counter expires, the AP 504 canbegin preparing one or more reference signals CTX 601-604 fortransmission to the STAs 506A-506E. If the intended CTX transmissionchannel has been idle since a time period 610 before the time that therandom back-off counter expired, then the AP 504 may transmit the one ormore reference signals CTX 601-604. Thus, once the random back-offcounter expires, at least one transmission is made over the primarychannel. In an embodiment, the time period 610 can be based on a PIFStime. The PIFS time can be chosen by the AP 504 and/or STAs 506A-506E.

FIGS. 6D-6F show another timing diagram in which aspects of the presentdisclosure can be employed. As described above, the primary channel (forexample, channel 526) and/or one or more of the secondary channels (forexample, channels 520, 522, and/or 524) can be used for transmissions bylegacy STAs and the secondary channels can be used for transmissions byhigh-efficiency STAs. The channels 520, 522, 524, and/or 526 may or maynot be contiguous. In an embodiment, one or more STAs 506A-506E canrequest the reference signals CTX 601-604 by transmitting arequest-to-send (RTX) 620. In various embodiments, an RTX can becompatible with legacy hardware. For example, the RTX can include an RTSas defined in IEEE 802.11, or can include another frame. In response,the AP 504 can transmit one or more solicited reference signals CTX601-604 to the STAs 506A-506E. The reference signals CTX 601-604 canindicate that STAs with data to send should being transmitting uponreceipt (or at a predetermined synchronization point after receipt). Inan embodiment, the STAs 506A-506E receive the reference signal CTX601-604 can begin to transmit the communications 510, 512, 514, and 518.As described in greater detail herein, CTX messages can identify whichSTAs are allowed to transmit and on which channels.

As shown in FIG. 6D, the AP 504 can transmit the reference signal CTX601-602 over a plurality of sub-channels, or even all sub-channels. InFIG. 6A, the STAs 506A-506E are only able to receive on their assignedchannel. Accordingly, the AP 504 transmits the reference signal CTX601-604 on all channels. In other embodiments, the STAs 506A-506E can beable to receive the reference signal on any channel. Accordingly, asshown in FIG. 6E, the AP 504 may transmit a single reference signal CTX602 on any sub-channel that can be received by the STAs 506A-506E. Invarious embodiments, the AP 504 may transmit a single reference signalCTX 602 on a different channel as the RTX 620. As shown in FIG. 6F, theAP 504 may transmit a single reference signal CTX 602 on the samechannel as the RTX 620.

In general, the AP 504 can be configured to transmit the referencesignals CTX 601-604 on a minimum number of sub-channels in order tonotify all target STAs. 506A-506E. In some embodiments, where more thanone sub-channel will suffice, the AP 504 may transmit a reference signalCTX 601 on the sub-channel with the least interference, or may transmitone or more redundant reference signals CTX 601-604.

In various embodiments, any STAs 506A-506E with data to send cantransmit the RTX 620, which can be compatible with legacy hardware suchas the STA 506E. In some embodiments, a STA transmits the RTX 620 on thesame channel on which it will transmit data. In other embodiments, theHEW STAs 506A-506E can transmit the RTX 620 on any available channel, achannel with the least interference, a first available channel accordingthe EDCA, etc.

The STAs 506A-506E can transmit the RTX according to EDCA, as discussedabove with respect to the CTX 601-604. Particularly, a random back-offcounter can be associated with a RTX transmission channel (such as theprimary channel 526 in FIG. 6F), as defined by the enhanced distributedchannel access (EDCA) procedure of IEEE 802.11. When the random back-offcounter expires, the STA 506E can transmit an RTX frame 620 in adesignated channel (for example, the primary channel) for transmissionto the AP 504. If additional channels (for example, non-primarychannels) RTX have been idle since a time period 610 (see FIG. 6C)before the time that the random back-off counter expired, then the STA506E may transmit the one or more RTX frames 620 on the primary and onthe available secondary channels. Upon reception of RTX, the AP 504 canrespond with a CTS or CTX frame in same set or subset of the channelwhere the RTX is received, and can send a CTX in one or more additionalchannels not within the channels where the RTX was received. Inparticular, the channels where the CTX is sent can include the channelswhere the medium was determined to be idle. In some embodiments, themedium can be determined to be idle by checking the channel for a PIFStime before the RTX reception or for a SIFS time after the RTXreception. In an embodiment, the time period 610 can be based on a PIFStime. The PIFS time can be chosen by the AP 504 and/or STAs 506A-506E.

In one embodiment, the CTX can include information granting transmissionto the STA 506E on the channels where the RTX was sent and can includeinformation granting transmission to other STAs on the channels wherethe RTX was not sent. In another embodiment, the CTX can includeinformation granting transmission for the STA 506 on a subset of the RTXchannels and may grant transmission to other STAs on the channels wherethe RTX was not sent.

The operation herein described, is advantageous at least because RTXframes can be an RTX in a legacy format and can be sent by a legacy STAs(such as the STA 506E), hence allowing a legacy STA to initiate an ULtransmit procedure. In some embodiments where the RTX is sent by alegacy STA, the AP 504 can respond with a CTX having a format compatiblewith the format of a legacy CTS, thus enabling consistent operation atthe STA. In various embodiments, the AP 504 can detect whether an RTXwas received from a legacy or high efficiency STA by, for example,comparing a transmit address with a stored lookup table. In otherembodiments, the AP 504 can detect whether an RTX was received from alegacy or high efficiency STA by reading an explicit indication embeddedin the legacy RTX format.

In various embodiments, the RTX can include a control frame includingone or more of the following fields: a frame control, a duration, asource address, a destination address, and an information payload. Theinformation payload can include one or more of the followingindications: a requested transmission time, a size of a transmissionqueue, a quality-of-service (QoS) indication for the requestedtransmission, and a requested transmission bandwidth. The QoS indicationcan include, for example, a traffic identifier (TID), a transport streamidentifier (TSID), and/or any other QoS Class). In various embodiments,the RTX control frame can omit one or more fields discussed above and/orinclude one or more fields not discussed above, including any of thefields discussed herein. A person having ordinary skill in the art willappreciate that the fields in the RTX control frame discussed above canbe of different suitable lengths, and can be in a different order. Invarious embodiments, the RTX frame can include a data frame and canadditionally include a high throughput control (HTC) field with anindication reverse decision grant (RDG)=1. In some embodiments, such aframe according to IEEE 802.11 can signal that a portion transmitopportunity indicated by the duration field and not used by the currenttransmission can be used by the recipient AP. The recipient AP can usethe transmit opportunity to initiate an uplink (UL) frequency divisionmultiple access (FDMA) transmission in any of the modes describedherein.

In some embodiments, the AP 504 and/or the STAs 506A-506E can determinea scheduled time at which the STAs 506A-506E should begin transmitting.For example, scheduling mechanisms can be used to define a time that theAP 504 should expect packets from the STAs 506A-506E. One schedulingmechanism can be based on a reference time agreed between the AP andeach individual STA via a management exchange. In various embodiments,the reference time can be periodic, intermittent, or randomly or pseudorandomly determined. Selection of the reference time can be achievedwith a protocol such as a target wakeup time (TWT) timing, which isdefined in the IEEE 802.11ah protocol. In some embodiments, the AP candefine the same reference time for multiple STAs by setting the TWT tosame value for multiple STAs. The TWT timing can be a time during whicha STA is scheduled to be awake. As another example, another schedulingmechanism can be based on defining a reference time for a group of STAsand an associated interval of time where access is restricted to thegroup of STAs. For example, such scheduling can be achieved with arestricted access window (RAW) timing, which is defined in the IEEE802.11ah protocol. The RAW timing can be an interval of time duringwhich access to a medium is restricted to a group of STAs. In variousembodiments, the interval of time can further be slotted and each slotassigned to one or more STAs, indicating that STAs can transmit UL dataat the start of the slot time.

At the reference time defined in any of above modes, STAs can be readyto receive a CTX frame for initiating the transmission. In someembodiments, STAs may start transmission without waiting for the CTX.Thus, in various embodiments, STAs can be transmitting at exactly thereference time, or it can perform a clear channel assessment procedureon the intended transmission channel, starting at the reference time. Invarious embodiments, the channel assessment may require a PIFS time orDIFS time. If the target channel is determined to be busy, the STA canrefrain from transmitting.

In another embodiment the STAs can be operating in HCCA mode, during aContention Free period. In thin case STAs are not allowed to access themedium until a CF-Poll message is received (802.11); the HCCA protocolcan be modified such that the CF-Poll message identifies more than oneSTAs for UL transmission at SIFS time after the CF-Poll frame. TheCF-Poll can be replaced with any of the CTX frames described herein.

The AP 504 may further include in management messages used to set up thescheduled time (for example, an RPS information element for RAW, TWTsetup messages for TWT, etc.) an indication of the channel allocationfor the benefit of the STAs. In another embodiment, the allocationindicated by the AP 504 in such a message can be in response to amessage transmitted by a STA to the AP 504 requesting the use of aspecific channel or simply the allocation of a channel. The message canbe included in a management frame.

The transmissions from the STAs 506A-506E may start at the timescheduled according to the TWT timing or the RAW timing. In anembodiment, the random back-off counter, the PIFS timing, and/or theAIFS timing can be used as described herein to determine whether thechannel has been idle for an appropriate amount of time. A benefit ofscheduling a transmission time based on the TWT timing or the RAW timingcan be that the AP 504 then knows when the STAs 506A-506E will be awake.In another embodiment, the STAs 506A-506E may not use the randomback-off counter, the PIFS timing, and/or the AIFS timing. In stillanother embodiment, the STAs 506A-506E may not use the PIFS timingand/or the AIFS timing on secondary channels.

In some embodiments, the AP 504 can transmit the reference signal CTX601-604 at the scheduled time. For example, the AP 504 can use the samescheduling mechanism as the STAs 506A-506E (for example, TWT timing orRAW timing) to determine when to transmit the reference signal CTX601-604. In an embodiment, the AP 504 can transmit the reference signalCTX 601-604 after sensing the medium as idle on the intended CTXchannel. In various embodiments, the AP 504 can transmit the referencesignal CTX as described above with respect to the RTX 620. In variousembodiments, the CTX message can be sent once at the beginning of theRAW and be used for time synch for all the slots in the RAW. In someembodiments, the CTX can be sent at the start of each slot, providingsynchronization and other information per each transmission.

Format of the Reference Signal

In various embodiments, the reference signals CTX 601-604 can include aclear-to-send frame, an extended clear-to-send frame, and/or anaggregated MAC protocol data unit (MPDU) including a clear-to-send frameand a new frame including an extended payload. In some embodiments,reference signals can be referred to as MAC messages. In variousembodiments, one or more reference signals CTX 601-604 can include thesame format (or compatible) as a legacy CTS as defined in 802.11. In oneembodiment, reference signals CTX 601-604 include a multicast MACaddress, for example, in a receiver address (RA) field of the CTS. Inanother embodiment, the reference signals CTX 601-604 can have sameformat (compatible format) as a CF-Poll frame as defined in 802.11 or aSynch frame as defined in 802.11ah. Poll frames can include a multicastreceiver address.

In various embodiments, the reference signals CTX 601-604 can includeone or more of the following indications: a deferral time for thirdparty STAs, one or more identifiers of STAs that are eligible totransmit via UL-FDMA at one certain (for example, a short inter-framespace (SIFS), a point coordination function (PCF) inter-frame space(PIFS), or longer) time after the reference signal frame, indications ofa power at which each of the STAs 506A-506E should transmit (forexample, an indication of the backoff with respect to a referencepower), an indication, for each STA, of the channel(s) and/or bandwidththe STAs 506A-506E should use to transmit, channel assignments for oneor more STAs, a time synchronization indication, an ACK policyindication for one or more STAs, an exact or maximum duration of thedata transmission, a number of spatial streams or number of space-timestreams for each STA, an indication of the length of all the informationfields included in the CTX, a timestamp or partial timestamp indicatinga time synchronization function (TSF) at the transmitter, etc. Theidentifier of STAs that are eligible to transmit can include a list ofaddresses (for example, MAC addressed, AIDs, partial or hashed AIDs,etc.) and/or one or more group identifiers. The group identifier caninclude, for example, a multicast MAC address previously associated to agroup of STAs and communicated to the STAs, or a group identifierpreviously defined and communicated to the STAs. The transmit powerindicator can include, for example, an absolute power indicator or anindication of a back-off from a STA nominal transmit power, which theSTAs 506A-506E can indicate. In various embodiments, one or more of theaforementioned payload elements can be negotiated or predeterminedbetween each STA 506A-506E and the AP 504. The payload elements can beincluded in an extended payload, or distributed in other fields.

FIG. 7A shows an example reference signal 700 that can be employedwithin the wireless communication systems of FIGS. 1, 2B, and 3. In theillustrated embodiment, the reference signal 700 includes a framecontrol field 710, a duration field 720, a receive address field 730, aframe check sequence (FCS) 740, and an extended payload 750. As shown,the frame control field 710 is two bytes long, the duration field 720 istwo bytes long, the receive address 720 is six bytes long, the FCS 740is four bytes long, and the extended payload 750 is a variable length.In various embodiments, the reference signal 700 can omit one or morefields shown in FIG. 7A and/or include one or more fields not shown inFIG. 7A, including any of the fields discussed herein. A person havingordinary skill in the art will appreciate that the fields in thereference signal 700 can be of different suitable lengths, and can be ina different order. In particular, the extended payload 750 can beomitted. In some embodiments, the reference signal 700 is aclear-to-send frame.

In various embodiments, the extended payload 750 can include one or moreof the payload elements or indications discussed above. Particularly,the extended payload can include a an identifier of STAs that areeligible to transmit via UL-FDMA at a time after the reference signalframe, an indication of a power at which the STAs 506A-506E shouldtransmit, an indication of the channel(s) and/or bandwidth the STAs506A-506E should use to transmit, specific channel assignments, and/or asynchronization indication. In various embodiments, the time after thereference signal frame can include a SIFS, a PIFS, or a time longer thanPIFS. In various embodiments, the time can be indicated by the AP 504(FIG. 5A) in the reference signal 700, or communicated by the AP 504 toSTAs in a previous message, or defined by the standard. The AP 504 candefine the time based on indications received from STAs

In an embodiment, the reference signal 700 can include an indicationthat the reference signal 700 includes an extended CTS frame includingthe extended payload 750. For example, the reference signal 700 can setone or more bits normally reserved in control frames to indicate thepresence of the extended payload 750. Accordingly, a legacy STA 506E canbe able to interpret at least some fields of the CTS frame.

In some embodiments, the CTX frame can include one or more padding bytesinserted after the information bytes. The purpose of the padding bytecan be to increase the length of the CTX, so as to provide additionaltime for the processing of the CTX information from the recipient STAs.The padding bytes can be identified as following the information bytes,according to the length of the information bytes indicated in one of theCTX fields.

In some embodiments, the reference signal 700 can omit the extendedpayload 750 and/or include a control wrapper frame indicating thepresence of a high-throughput control (HTC) field. The HTC field mayprovide four bytes that can be used to embed identifiers of target STAsinformation. As another example, a special CTS message may includeadditional information after the FCS field.

In some embodiments the CTX message can include a CTS message with an HTControl field (for example, as defined in IEEE 802.11). The presence ofthe HT Control (HTC) field in the CTS can be identified, for example asdefined in the IEEE 802.11 standard. The HTC field can be overridden tocarry one or more of the indications listed above. The fact that the HTCis overridden to signal the above information can be indicated by one ormore of: the type of PHY preamble used for the transmission, and one ormore bits in the HTC control field itself.

In some embodiments, the CTX can be a data frame and can include an HTCfield with reverse decision grant (RDG)=1, indicating that the AP isallowing the recipient to use the remainder of the duration time for atransmission. In particular, this may act as the trigger indication forthe UL FDMA transmissions. Moreover, the HTC field can be overridden tocarry the necessary information, as described above.

In some embodiments, the CTX frame can be the same or similar to a powersave multi-poll (PSMP) frame (for example, as defined by the 802.11standard), wherein the PSMP-UTT start offset within a STA info fieldidentifies the start time for the UL FDMA transmissions, the PSMP UTTduration identifies the duration of the UL FDMA transmission and the STAID field may include an identifier of the STAs allowed to transmit.Moreover the reserved bits can be used to indicate a power backoff, atransmission bandwidth (BW), and/or a channel allocation. Multiple STAinfo fields can be included in a same PSMP frame, with a same value ofstart offset and duration, hence indicating that multiple STAs cantransmit in UL FDMA at the indicated time.

FIG. 7B shows exemplary reference signal formats and fields that can beemployed within the wireless communication systems of FIGS. 1, 2B, and3. In the illustrated embodiment, the reference signal is the same orsimilar to a PSMP frame, as discussed above. In various embodiments, thereference signal of FIG. 7B can omit one or more fields shown in FIG. 7Band/or include one or more fields not shown in FIG. 7B, including any ofthe fields discussed herein. A person having ordinary skill in the artwill appreciate that the fields in the reference signal of FIG. 7B canbe of different suitable lengths, and can be in a different order.

As shown in FIG. 7B, a PSMP parameter set fixed field can include afive-bit number of STAs field N_STA, a six-bit More PSMP field, and a10-bit PSMP Sequence Duration field. A PSMP STA Info fixed field, whengroup addressed, can include a two-bit STA_INFO Type field (set to “1”),an 11-bit PSMP-DTT Start Offset field, an 8-bit PSMP-DTT Duration field,and a 43-bit PSMP Group Address ID. The PSMP STA Info fixed field, whenindividually addressed, can include a two-bit STA_INFO Type field (setto “2”), an 11-bit PSMP-DTT Start Offset field, an 8-bit PSMP-DTTDuration field, a 16-bit STA_ID field, an 11-bit PSMP-UTT Start Offsetfield, a 10-bit PSMP-UTT Duration field, and six reserved bits. A PSMPframe Action field can include a category field, an HT Action field, aPSMP Parameter Set, and one or more PSMP STA Info fields repeated N_STAtimes.

In various embodiments, a new value of the STA info type can be used toindicate that the STA info field includes the start offset field, theduration field, and a field identifying the multiple STAs allowed totransmit (for example, as a group identifier, a list of addresses orpartial addresses, etc.). In some embodiments, the group of destinationSTAs can be identified by the receive address (RA) of the frame itself.In various embodiments, the reference signal can otherwise include therest of the PSMP frame format. Advantageously, the use of the PSMP frameallows indicating multiple UL and DL schedules for UL and DLtransmissions.

FIG. 7C shows an example reference signal 760 that can be employedwithin the wireless communication systems of FIGS. 1, 2B, and 3. In theillustrated embodiment, the reference signal 760 includes the framecontrol field 710, the duration field 720, the receive address field730, a transmit address field 762, a length field 764, a STA info field766, one or more optional padding bits 768, and the frame check sequence(FCS) 740. As shown, the frame control field 710 is two bytes long, theduration field 720 is two bytes long, the receive address 720 is sixbytes long, the transmit address field 762 is six bytes long, the lengthfield 764 is one byte long, the STA info field is a variable length N*X,the padding bits 768 are a variable length M, and the FCS 740 is fourbytes long. In various embodiments, the reference signal 760 can omitone or more fields shown in FIG. 7C and/or include one or more fieldsnot shown in FIG. 7C, including any of the fields discussed herein. Aperson having ordinary skill in the art will appreciate that the fieldsin the reference signal 760 can be of different suitable lengths, andcan be in a different order. In particular, the receive address field730, the length field 764, and/or the padding bits 768 can be omitted.In some embodiments, the reference signal 760 is a clear-to-send frame.

In various embodiments, the RA 730 is present only in case it is usedfor identifying the group of recipient STAs. The length field 764 mayinclude either a length N in bytes of the information portion 766, or anumber X of STA info fields. The STA info field 766 can include one ormore of the per-STA indications listed above. In various embodiments, itcan have the same length for each STA. The padding bits 768 can includeM byes of padding, to increase the frame length.

In one embodiment, if the CTX message is sent over multiple channels,any of the following is possible: it can be sent as a single frame witha transmission BW spanning the total transmission BW allocated for ULtransmissions; it can be sent as a duplicate across all the channelsallocated for UL transmissions, i.e., the content of each CTX is exactlythe same across channels; and it can be different per-channel, carryingdifferent information for different STAs receiving on differentchannels. In various embodiments, CTSs sent on different channels witheither different BW or different information can have a differentlength, which may be contrary to the purpose of providing a referencesynchronization time to all the STA for the UL transmission. Thus, inorder for all the CTSs to be of same length, each CTX can include anumber of padding bytes so that the length of all the CTXs is same.

In another embodiment, the CTX frame can be followed by an additional“filler” frame sent by the same sender of the CTX, after a SIFS time.The filler frame can serve to keep the medium busy and provideadditional time to the STAs for the processing and interpretation of theCTX information and for the preparation of the following ULtransmission. In various embodiments, the filler frame can be any of annull data packet (NDP), CTS, or other control frame. The filler framecan also provide additional protection for the upcoming transmissions.

In various embodiments, the need for, or inclusion of, padding and/or afiller frame can be indicated by a STA to the AP with an indication atassociation (for example, in an association request) or through amanagement exchange. The STA can also indicate the amount of timerequired for processing, which can determine the amount of paddingrequired.

When the transmission is initiated by the AP with a CTX, advantageouslythe AP can schedule transmissions at a time where multiple STAs areawake and have available data, hence maximizing the efficiency. Whenusing scheduled modes, the AP may also indicate to the STAs that notransmission are allowed outside the scheduled periods. This indicationcan be included in the beacon or included in the setup phase (see“Setup,” below) for each STA.

Transmission Eligibility

As discussed above, the AP 504 can indicate a list of STAs that areeligible to transmit, for example in the reference signal 700 (FIG. 7A)or during transmission scheduling. STAs 506A-506E can indicate that theyhave data to transmit in a QoS control field of any data packet sent bythe STAs 506A-506E to the AP 504. In an embodiment, the STAs 506A-506Ecan transmit a QoS null data frame to the AP 504, which can include theQoS control field, to indicate that the STA 506A-506E has buffered unitsfor transmission. In some embodiments, the STAs 506A-506E can transmitthe QoS control field in any data frame using regular contentionprocedures. The AP 504 can receive the QoS control field, determinewhich STAs 506A-506E have data to transmit, and determine which STAs506A-506E to indicate for transmission eligibility.

In some embodiments, the STAs 506A-506E can indicate that they have datato transmit by encoding an uplink data indication in a power-save poll(PS-Poll) frame according to 802.11ah. In some embodiments, the STAs506A-506E can indicate that they have data to transmit by transmittinganother frame via regular CSMA contention. In some embodiments, the AP504 can indicate a window during which STAs 506A-506E should transmitindications that they have buffered units. The window of time can beadvertised in a Beacon and be essentially similar to a RAW in someembodiments. The advertisement can be achieved, for example, by using anRPS information element as defined by the IEEE 802.11ah standard, withthe following change: the type of the RAW is indicated to be for ULindication only. The AP can also schedule a TWT with each individual STAfor allowing the STA to send an UL indication.

Channel Allocation

FIG. 8 shows another timing diagram 850 in which aspects of the presentdisclosure can be employed. As illustrated in FIG. 8, the AP 504transmits channel allocation messages 802, 804, 806, and 808 on each ofthe channels 520, 522, 524, and 526, respectively. The channelallocation messages CHA 802, 804, 806, and 808 may provide informationto the STAs 506A-506E regarding which channel is allocated to which STA.In some embodiments, the channel allocation messages 802, 804, 806,and/or 808 can be the MAC message or reference signal 800 (FIG. 8)described above.

In an embodiment, if the new PHY layer preamble 528 is available, thePHY layer preamble 528 includes a group identification field thatcorresponds to a channel allocation of the STAs of the group.

In an embodiment, the channels can be pre-allocated, selected by theSTAs 506A-506E, and/or selected by the AP 506A-506E and explicitlymessaged via the channel allocation messages 802, 804, 806, and/or 808.The channel allocation messages 802, 804, 806, and/or 808 can be sent atany time prior to the transmission by each STA. In another embodiment,the AP 504 can include channel allocation in the reference signals CTX601-604 (FIGS. 6A-6F) or MAC frames 802, 804, 806, and/or 808 sentimmediately before the data transmission 510, 512, 514, and/or 518. Thechannel allocation can be indicated by one or more MAC addresses, AIDs,partial or hashed AIDs, and corresponding channel identifiers.

In another embodiment, a group can be defined that includes multipleSTAs, each STA can be assigned a position in the group, and the groupcan be identified by a group ID or by a multicast MAC address. Thus, achannel allocated to a STA can be identified by the group ID ormulticast MAC address, and further by the position of the STA in thegroup identified by the group ID. Messages for setting up the groupdefinitions can be sent at any time before the UL-FDMA datatransmissions 510, 512, 514, and/or 518 and can be carried by managementframes. Messages for indicating channel allocation for a certain datatransmission can be conveyed by management or control frames sent beforethe data transmission 510, 512, 514, and/or 518 (for example, theseframes may not be transmitted based on SIFS or PIFS as described above),or can be sent on a synchronization or MAC frame immediately precedingthe data transmission 510, 512, 514, and/or 518. In embodiments wherechannel allocation is included in the reference messages CTX 601-604 ora CF-Poll frame, the receiver address can include a multicast MACaddress corresponding to a group and hence identifying the channel forthe STA.

In embodiments where the channels are pre-allocated, and when the numberof STAs is above a threshold and traffic requests from the STAs aresimilar, then a random static allocation can be used (for example, eachSTA is allocated to a channel, semi-statically). The AP 504 may indicateto the STAs 506A-506E which station is allocated to which channel (forexample, via the channel allocation messages 802, 804, 806, and/or 808).If the channels are selected by the STAs 506A-506E, STAs 506A-506E mayselect and wait on a channel preferred by the respective STA 506A-506E.The STAs 506A-506E may explicitly or implicitly (for example, via anytransmission) notify the AP 504 of their presence on the respectivechannel.

In embodiments where the allocation is explicitly messaged, the channelallocation messages 802, 804, 806, and/or 808 can be sent on each of thechannels or just a primary channel. Where the STAs 506A-506E implicitlynotify the AP 504 of their presence, the AP 504 may know of a STA506A-506E location based on reception of any data, control, and/ormanagement frame transmitted by the STA 506A-506E for regular operation.In other words, the data, control, and/or management frame may notnecessarily be designed for channel indication. In embodiments where theSTAs 506A-506E are able to receive frames on multiple channels, thereception of a reference signal addressed to a STA on an certain channelcan implicitly indicate that the certain channel is allocated to theaddressed STA. Particularly, the AP 504 can transmit multiple referenceframes CTX on multiple channels, each addressed to a different STA,thereby defining the channel allocation.

Protection Stage

In various embodiments, as discussed above with respect to FIGS. 6D-6Frequest to send (RTX) and CTX messages are used by the AP 504 and theSTAs 506A-506E to ensure that a given channel is free. The durationfield in RTX and CTS can indicate a duration that covers the immediatelyfollowing transmission, plus the required acknowledgments.

Acknowledgment Stage

In an embodiment, restrictions can be placed on the duration of apacket. In some embodiments, transmissions by the STAs 506A-506E havedifferent lengths. In other embodiments, transmissions by the STAs506A-506E have the same length.

Following the UL communications 510, 512, 514, and/or 518, the AP 504may respond with a block acknowledgment (BA) acknowledging that the DLcommunication was received. The AP 504 may respond with the BA on itsown volition or can be prompted to by the STAs 506A-506E (for example,via a block acknowledgment request (BAR)). If the STAs 506A-506E are allable to receive on any channel, or are all able to receive on at least asame common channel (such as the primary channel), the AP 504 maybroadcast a single block acknowledgment (BBA). The BBA frame carriesblock acknowledgment indications for multiple STAs, possibly all theSTAs that sent data in UL. Additional information regarding BBA framescan be found in U.S. Provisional Application No. 61/267,734, filed Dec.8, 2009, which is hereby incorporated by reference, and in anapplication entitled “METHOD AND APPARATUS FOR MULTICAST BLOCKACKNOWLEDGEMENT,” attached hereto.

In an embodiment, the BBA can be sent on the primary channel. In variousembodiments, APs 504 and/or STAs 506A-506E can transmit BAs, BARs,and/or BBAs in a legacy or high-efficiency physical protocol data unit(PPDU) format. In some embodiments where the APs 504 and/or STAs506A-506E transmit BAs, BARs, and/or BBAs in high efficiency PPDUformat, the bandwidth can be smaller than 20 MHz. Moreover differentBAs, BARs, and/or BBAs can have different durations, which can depend ona bandwidth used for transmission. Timing diagrams included herein, andthe various messages they show, are not to scale.

FIGS. 9A-9C show additional timing diagrams in which aspects of thepresent disclosure can be employed. In particular, FIGS. 9A-9Cillustrate the use of BAs, BARs, and BBAs as described herein. In anembodiment, transmissions 51, 512, 514, and 518 do not end at the sametime, the AP 504 responds immediately with a BA after the ULcommunication is complete. The AP 504 then responds to the remainingtransmissions with a BA after receiving a BAR. The STAs 506A-506E maytransmit the BAR on the channel that the UL communication wastransmitted on, the primary channel, the high-efficiency primary channel(for example, a primary channel defined for use by the high-efficiencydevices), and/or any other channel.

For example, as illustrated in FIG. 9A, the AP 504 may respond with a BA904A after the UL communication 514 is complete. After the BA 904A hasbeen received by the STA 506C, the STA 506C may transmit a BAR 902B tothe AP 504 on the channel 522, which is the channel that the DLcommunication 512 was received by the STA 506B. Once the AP 504 receivesthe BAR 902B, the AP 504 may respond with a BA 904B. The BAR and BAcycle then continues for the remaining STAs (for example, STA 506A andSTA 506E). The AP 504 can instruct the STAs 506A-506E to set theacknowledgment policy of the data transmitted by the STAs 506A-506E suchthat no more than one STA 506A-506E requests an immediate BA. In someembodiments, all the BA policies can be set to BA (no immediate responserequired), but the AP can nevertheless select one or more STAs and sendan immediate BA to them. The AP 504, after receiving an immediateacknowledgment request or BAR, may transmit the acknowledgment or BA onthe same channel where data was received and/or on the primary channel.An additional BAR can be sent by the STAs 506A-506E on the primarychannel and/or on one or more of the secondary channels, such as thesame channel where data was transmitted. In this case, the AP 504 maytransmit the acknowledgment or BA on the same channel where the BAR wasreceived and/or on the primary channel.

In an embodiment, if the communications 510, 512, 514, and 518 end at ornear the same time and/or where STAs 506A-506E can only receive onlimited sub-channels, the AP 504 can respond with a BA on eachsub-channel after the UL communications are complete (for example, endof transmission is a trigger for the AP 504 to send the BAs). The BAscan be transmitted on the same channel as the channel where the ULcommunication was received. For example, as illustrated in FIG. 9B, theAP 504 response with a BA 904A-904D immediately after the ULcommunications 510, 512, 514, and 518 are complete. The BAs 904A-904Dcan be transmitted concurrently.

In embodiments where all STAs 506A-506E are able to decode a packet onany channel, or the primary channel 526, the AP 504 can broadcast a BBAafter the UL communications 510, 512, 514, and 518 are complete. Forexample, as illustrated in FIG. 9C, the AP 504 transmits the BBA 904E onthe primary channel 526 in response to the termination of the ULcommunications 510, 512, 514, and 518 are complete. Because all STAs506A-506E can decode the BBA 904E, only one is transmitted. Where one ofthe STAs 506A-506E is a legacy STA, the AP 504 can instruct the highefficiency STAs to have a transmission that is shorter than atransmission of the legacy STA. The duration of transmission from thelegacy STA can be inferred from a duration field set in an RTX frame.Moreover the AP 504 can instruct high-efficiency STAs to use a no-ACKpolicy.

Use Cases

In an embodiment, the UL FDM protocol described herein with respect toFIGS. 5A-9C is implemented in several applications. For example, a BSAmay include legacy STAs and high-efficiency STAs. The UL FDM protocolmay use otherwise unused bandwidth in the communication medium byassigning some of the STAs to a portion of the otherwise unusedbandwidth. This may allow the legacy STAs and/or the high-efficiencySTAs to communicate concurrently. This can be beneficial if the BSSrange of the wireless network is restricted to high rate users.

As another example, frequency diversity can be achieved if the PHY layeruses a tone interleaved approach. With frequency diversity, a frequencyhopping system is created that requires minimal interferencecoordination. Tones can be divided into two or more subsets. A first STAmay transmit and/or receive data via tones in the first subset and asecond STA may transmit and/or receive data via tones in the secondsubset. As long as the first subset and the second subset do notoverlap, interference can be avoided.

Setup

In various embodiments, the UL FDMA transmission can indicate specificcapabilities (for example, requested or required) to the STA. STAs thatdo not have the indicated capabilities may not use the UL FDMAtransmission. Hence, the UL FDMA transmission may not be used by all theSTAs.

In some embodiments, the AP can determine which STAs are potentiallyparticipating in the UL FDMA transmission. Each STA can indicate itscapability by setting one or more bits in a Probe/Association request.In some embodiments, STAs can indicate the willingness to participate inUL FDMA transmission by sending a request to the AP through a managementframe.

In various embodiments, the request can be carried in an additionalinformation field during the setup of a traffic specification (TSPEC),for example, as defined by the IEEE 802.11 specification. In variousembodiments, the request can also be carried during setup of an add BA(ADDBA) procedure. In various embodiments, the request can be carriedthough a new management agreement, wherein the STA sends a managementframe to AP indicating the request and additional relevant parametersfor the operation, such as transmit power capability, traffic pattern,QoS for which the procedure is requested, time to process the CTX, etc.

In some embodiments, the STA advertising a capability may not requestthe initiation of the use of UL FDMA. Instead, the AP may request theSTA the parameters required for the UL FDMA operation. In someembodiments, the STA can be forced to accept the request. In someembodiments, the STA may reject the request. In various embodiments, theAP can also advertise its capability to receive UL FDMA transmissions.Such advertisement can be indicated by one or more bits in proberesponse, association response and/or beacons.

Operation

In various embodiments, all options discussed herein can be combined inan efficient way of using UL-FDMA. In particular, as described above,the AP can define dedicated intervals of time for DL/UL transmissionsand for collecting requests from the STAs. In one embodiment, the AP canschedule the operations such that the following sequence of operationsis achieved, wherein parentheses indicate optionality, brackets indicatethat the enclosed sequence can be repeated multiple times within abeacon interval, and operations are separated by semicolons: Beacon;[(restricted access interval for PS-Polls or UL requests); restrictedaccess interval for DL transmission; restricted access interval for ULtransmissions]. In one embodiment, the AP can schedule the operationssuch that the following sequence of operations is achieved, whereinparentheses indicate optionality, brackets indicate that the enclosedsequence can be repeated multiple times within a beacon interval, andoperations are separated by semicolons: Beacon; [(restricted accessinterval for PS-Polls); restricted access interval for DL transmission;(restricted access interval for UL request); restricted access intervalfor UL transmissions]. In one embodiment, the AP can schedule theoperations as shown in FIG. 9D.

FIG. 9D shows an additional timing diagram 990 in which aspects of thepresent disclosure can be employed. In various embodiments, the AP canprotect or hold the medium for the entire sequence by means of settingthe NAV for all non-scheduled STAs or maintaining no more than SIFS orPIFS time of medium idle across the entire sequence. As shown in FIG.9D, during a HEW transmit opportunity (TXOP) 992 includes restrictedaccess intervals for DL transmission 994, SIFS time (or shorter period)996, a HEW UL random access interval 998, and a HEW UL dedicated channelaccess interval 999.

As shown in FIG. 9D, the AP can gain access to the medium throughregular contention or through a predefined schedule. The AP may thenprotect a certain interval of time referred to as transmissionopportunity (TXOP) 992. The protection may be achieved by sending aframe that can set the NAV or through a scheduling that prevents certainundesired STAs to transmit during the TXOP 992. During the TXOP 992, theAP can schedule separate intervals of time for UL communication, DLcommunication, and for collecting requests from STAs for an ULcommunication. Within the UL communication interval, any of the modesdescribed herein can be used for UL FDMA transmissions. Within the timereserved for indication of UL traffic, a STA may use any of the methodsdescribed herein (QoS Null, PS-Poll with uplink indication, and Datawith More Data field set). Moreover the transmission of such indicationmay be scheduled by AP or can occur though contention. The AP can retaincontrol on the medium by making sure that no time greater than SIFS orPIFS is unused within the TXOP 992.

Flowcharts

FIG. 10 shows a flowchart 1000 for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 500 of FIG. 5. The method can be implemented in whole or in partby the devices described herein, such as the wireless device 402 shownin FIG. 4. Although the illustrated method is described herein withreference to the wireless communication system 100 discussed above withrespect to FIG. 1, the wireless communication systems 200, 250, 300, and500 discussed above with respect to FIGS. 2-3 and 5A, and the wirelessdevice 402 discussed above with respect to FIG. 4, a person havingordinary skill in the art will appreciate that the illustrated methodcan be implemented by another device described herein, or any othersuitable device. Although the illustrated method is described hereinwith reference to a particular order, in various embodiments, blocksherein can be performed in a different order, or omitted, and additionalblocks can be added.

First, at block 1010, an access point determines a performancecharacteristic for each wireless device in a set of wireless devicesassociated with the access point. For example, the AP 504 can determineone or more performance characteristics for each STA 506A-506E in theBSA 502. In various embodiments, the performance characteristic caninclude physical and/or RF characteristics such as, for example, asignal-to-interference-plus-noise ratio (SINR), an RF geometry, areceived signal strength indicator (RSSI), a modulation and codingscheme (MCS) value, an interference level, a signal level, atransmission capability, etc.

Then, at block 1020, the access point categorizes each wireless devicein the set into at least a first and second subset of wireless devicesbased on the performance characteristic. The first set of wirelessdevices can have a higher performance characteristic than the second setof wireless devices. For example, the AP 504 can categorize each STA506A-506E in the BSA 502 into the first and second subsets. In anembodiment, the first subset of wireless devices can include inner-celldevices and the second subset of wireless devices can include cell-edgedevices. For example, the AP 504 could categorize the STAs 506A-506C asinner-cell devices because they are physically close and might havestrong signal strength. In contrast, the AP 504 could categorize theSTAs 506D-506E as cell-edge devices because they are farther away andcan might have a lower SINR.

In various embodiments, the first subset of wireless devices can have ahigher signal-to-interference-plus-noise-ratio (SINR), a higher geometryrating, a higher received signal strength indicator (RSSI) than thesecond subset of wireless devices, or a greater transmission capability.In one embodiment, the first subset of wireless devices can have ahigher modulation and coding scheme (MCS) value than the second subsetof wireless devices. In one embodiment, the first subset of wirelessdevices can have a lower interference than the second subset of wirelessdevices.

In some embodiments, the access point can assign the second set ofwireless frequencies to the second subset of wireless devices. Forexample, the AP 504 can assign the channel 526 to the STA 506E. The AP504 can assign channels in coordination with other devices, based onobserved interference, etc.

In some embodiments, the access point can receive an indication of thesecond set of wireless frequencies from at least one device in thesecond subset of wireless devices. For example, the STA 506E can makeits own channel assignment, for example, based on observed interference.The STA 506E can transmit the channel assignment to the AP 504.

In some embodiments, the access point can transmit an indication of thesecond set of wireless frequencies to one or more devices not associatedwith the access point. For example, with reference to FIG. 2B, the AP254A can make one or more channel assignments and can indicate thechannel assignments of associated cell-edge devices to, for example, theAP 254C and/or the STA 256G. In some embodiments, the access point canreceive an indication of the second set of wireless frequencies from oneor more devices not associated with the access point. For example, theSTA 256G could instead make one or more channel assignments and cannotify the AP 254A and/or the STA 256A.

In some embodiments, at least one wireless device in the second subsetof wireless devices can include a legacy device incapable oftransmitting on the entire first subset of frequencies. Returning toFIG. 5A, for example, the STA 506E can be a legacy device. In someembodiments, the STA 506E can be incapable of transmitting on the entirefirst subset of frequencies such as, for example, where it must transmiton a primary channel.

In some embodiments, the access point can receive a ready-to-send (RTX)frame from at least one device in the second subset of wireless devices.For example, the STA 506E can generate the RTX 620 (FIG. 6F) andtransmit it to the AP 604. In some embodiments, the access point cantransmit a reference signal to at least one device in the second subsetof wireless devices. For example, the AP 504 can transmit the referencesignal CTX 601, in some instances in response to the RTX 620 bytransmitting.

In various embodiments, the reference signal can include an indicationof a deferral time for third party devices. In an embodiment, thereference signal can include an indication of devices that are eligibleto transmit at a particular time. In an embodiment, the reference signalcan include an assignment of channels to one or more devices in thesecond subset of wireless devices. For example, the extended payload 750(FIG. 7A) can include one or more channel assignments or transmitauthorizations. In some embodiments, the transmit authorizations caninclude a list of addresses of devices eligible to transmit at aparticular time (for example, the next SIFS time). The transmitauthorizations can include a group identifier defined in advance, forexample, by the AP 504.

In an embodiment, the reference signal can include an indication of apower level at which at least one device should transmit. For example,the extended payload 750 can include an indication of a back-off fromthe STA's 506E nominal transmit power, which the STA 506E can indicateto the AP 504.

In various embodiments, the reference signal can include an indicationof a transmission time of at least one device in the second subset ofwireless devices. In an embodiment, the reference signal can include aclear-to-send frame (CTS). In an embodiment, the reference signal caninclude a clear-to-send frame (CTS) and an extended payload comprisingone or more payload elements. In an embodiment, the reference signal caninclude a clear-to-send frame (CTS) comprising a high-throughput control(HTC) field indicating one or more target devices. In an embodiment, thereference signal can include an aggregated media access control protocoldata unit (A-MPDU) comprising a clear-to-send frame (CTS) and one ormore payload elements. For example, the reference signal can include thereference signal 700, described above with respect to FIG. 7A.

Next, at block 1130, the access point receives communications from thefirst subset of wireless devices on a first set of wireless frequencies.For example, the AP 504 can receive communications 510 from the STA506A. In some embodiments, the communications 510 can utilize an entireavailable bandwidth (for example, channels 308, 310, 312, and 314 ofFIG. 3). In some embodiments, the communications 510 can utilize only aportion of available bandwidth.

Thereafter, at block 1140, the access point receives communications fromthe second subset of wireless devices on a second set of wirelessfrequencies. The second set of wireless frequencies is a subset of thefirst. For example, the first subset can include channels 526, 524, and522. The second subset can include channel 526. Accordingly, the AP 504can receive the communication 518 from the STA 506E on the channel 526.

In other embodiments, the first and second sets of wireless frequenciescan be mutually exclusive. For example, the first subset can includechannels 522 and 520, and the second subset can include channels 526 and524. Accordingly, the first set of wireless devices can contend normallyfor a portion of the available bandwidth while the second set ofwireless devices can use FDMA to access another portion of the availablebandwidth.

In some embodiments, the access point can concurrently receivecommunications from each device in the second subset of wirelessdevices. For example, the AP 504 can concurrently receive thecommunication 518 from the STA 506E on the channel 524, and can receivethe communication 516 from the STA 506D on the channel 524 (not shown).In some embodiment, the access point can schedule a time at which toreceive communications from the second subset of wireless devices.

In one embodiment, the access point can schedule a time at which toreceive communications from the second subset of wireless devices andtransmit a reference signal to at least one device in the second subsetof wireless devices at the scheduled time. For example, at the scheduledtransmit time, the AP 504 can transmit the reference signal 700 tosynchronize the STAs 506A-506E. In one embodiment, the access point canreceive, from at least one device in the second subset of wirelessdevices, an indication that the at least one device can be ready to senddata. For example, the AP 504 can receive the RTX 620 from the STA 506E(FIG. 6F).

In some embodiments, the access point can receive, from at least onedevice in the second subset of wireless devices, a quality-of-service(QoS) field indicating that the at least one device can be ready to senddata. For example, the STA 506E can transmit a QoS field to the AP 504to indicate that it has data to transmit. In another embodiment, theaccess point can receive, from at least one device in the second subsetof wireless devices, a power-save poll (PS-Poll) frame indicating thatthe at least one device can be ready to send data. For example, the STA506E can transmit the PS-Poll frame to the AP 504 to indicate that ithas data to transmit.

In various embodiments, the first subset of wireless frequencies caninclude a 20 or 40 or 80 MHz channel according to an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 standard. In variousembodiments, the first and second subset of wireless frequencies can bewithin an operating bandwidth of the access point.

In various embodiments, the first and second communications start at thesame time indicated by the reference signal, within a margin oftransmission time error. For example, the margin of transmission timeerror can be a threshold value within which the first and secondcommunications start at substantially the same time. In variousembodiments, the first and second communications start at differenttimes.

In various embodiments, the first and second communications end at thesame time indicated by the reference signal, within a margin oftransmission time error. For example, the margin of transmission timeerror can be a threshold value within which the first and secondcommunications end at substantially the same time. In variousembodiments, the first and second communications end at different times.

In various embodiments the reference can be sent by the access pointaccording to a sense multiple access (CSMA) mechanism. In variousembodiments the reference signal can be sent by the access point at atime previously scheduled with at least the first device via managementsignaling. In various embodiments, the reference signal is sent at leaston a primary channel. In various embodiments, the reference signal issent on a primary channel and on all or a portion of secondary channelsthat are idle for a sensing time before the transmission. In variousembodiments, the reference signal is sent on channels compatible withthe first and second devices.

In various embodiments, the at least the first device indicates to theaccess point a channel use capability. In various embodiments, thereference signal is sent on idle channels only. In various embodiments,the reference signal is sent on a primary channel only, with anindication that only idle channels are to be used.

In an embodiment, the method shown in FIG. 10 can be implemented in awireless device that can include a determining circuit, a categorizingcircuit, and a receiving circuit. Those skilled in the art willappreciate that a wireless device can have more components than thesimplified wireless device described herein. The wireless devicedescribed herein includes only those components useful for describingsome prominent features of implementations within the scope of theclaims.

The determining circuit can be configured to determine the performancecharacteristic. In some embodiments, the generating circuit can beconfigured to perform at least block 1010 of FIG. 10. The determiningcircuit can include one or more of the processor 404 (FIG. 4), the DSP420, the signal detector 418 (FIG. 4), the receiver 412 (FIG. 4), andthe memory 406 (FIG. 4). In some implementations, means for determiningcan include the determining circuit.

The categorizing circuit can be configured to categorize each wirelessdevice. In some embodiments, the categorizing circuit can be configuredto perform at least block 1020 of FIG. 10. The categorizing circuit caninclude one or more of the processor 404 (FIG. 4), the DSP 420, and thememory 406 (FIG. 4). In some implementations, means for categorizing caninclude the categorizing circuit.

The receiving circuit can be configured to receive communications fromthe first and second subsets of wireless devices. In some embodiments,the receiving circuit can be configured to perform at least blocks 1030and/or 1040 of FIG. 10. The receiving circuit can include one or more ofthe receiver 412 (FIG. 4), the antenna 416 (FIG. 4), and the transceiver414 (FIG. 4). In some implementations, means for receiving can includethe receiving circuit.

FIG. 11 shows a flowchart 1100 for another exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 500 of FIG. 5. The method can be implemented in whole or in partby the devices described herein, such as the wireless device 402 shownin FIG. 4. Although the illustrated method can be described herein withreference to the wireless communication system 110 discussed above withrespect to FIG. 1, the wireless communication systems 200, 250, 300, and500 discussed above with respect to FIGS. 2-3 and 5A, and the wirelessdevice 402 discussed above with respect to FIG. 4, a person havingordinary skill in the art will appreciate that the illustrated methodcan be implemented by another device described herein, or any othersuitable device. Although the illustrated method can be described hereinwith reference to a particular order, in various embodiments, blocksherein can be performed in a different order, or omitted, and additionalblocks can be added.

First, at block 1110, a first wireless device receives a referencesignal from an associated access point. The reference signal indicatesof a time of joint transmission with at least a second wireless device.For example, the STA 506E can receive the reference signal CTX 601 (FIG.6C) from the AP 504.

Then, at block 1120, the first wireless device transmits a firstcommunication to the access point based on the reference signal. Thecommunication utilizes a first subset of wireless frequencies availablefor use, and is concurrent with a second communication from the secondwireless device. The second communication utilizes a second subset ofwireless frequencies mutually exclusive with the first subset. Forexample, the STA 506E can transmit the communication 518 on the primarychannel 526. Meanwhile, the STA 506A can transmit the communication 510on the channel 524. The channel 524 includes a set of frequencies thatis mutually exclusive with the set of frequencies in the channel 526. Inan embodiment, the first wireless device can receive the referencesignal on the second subset of wireless frequencies. For example, theSTA 506E can receive the reference signal CTX 602 on the channel 524(FIG. 6B), even though the STA 506E does not transmit on the secondarychannel 524.

In an embodiment, the first wireless device can transmit a request forthe reference signal to the access point. For example, the STA 506E cantransmit the RTX 620 (FIG. 6F) on the channel 526. In an embodiment, thefirst wireless device can transmit a request for the reference signal tothe access point on the second subset of wireless frequencies. Forexample, the STA 506E can transmit the RTX 620 on the channel 524 (FIG.6D) even though the STA 506E does not transmit the communication 518 onthe channel 524. In an embodiment, the first wireless device cantransmit a ready-to-send (RTX) frame to the access point. For example,the STA 506E can transmit the RTX 620.

In an embodiment, the first wireless device can receive an indication ofthe first subset of wireless frequencies from the access point. Forexample, the AP 504 can assign the STA 506E the channel 526 fortransmitting the communication 518. The AP 504 can indicate the channel526 in, for example, the reference signal 700 described above withrespect to FIG. 7A. In an embodiment, the first wireless device canreceive an indication of the first set of wireless frequencies from oneor more devices not associated with the access point. For example, withreference to FIG. 2B, the STA 256A can receive a channel assignment fromthe STA 256G and/or the AP 254C.

In an embodiment, the first wireless device can detect an interferencelevel on one or more wireless frequencies and determine the first subsetof wireless frequencies based on the interference level. For example,with reference to FIG. 6A, the STA 506E might detect relatively highinterference levels on the channels 524, 522, and 520, as compared tothe channel 526. Accordingly, the STA 506E might determine that itshould transmit the communication 518 on the channel 526.

In an embodiment, the first wireless device can determine the firstsubset of wireless frequencies based on a tone interleaved channel withfrequency hopping. For example, the STA 506E might determine to hopbetween the channel 524 and the channel 526. As another example, thechannel 526 can include a tone interleaved channel with built-infrequency hopping. Accordingly, the STA 506E can stay on the channel 526as the particular frequencies in channel 526 change.

In an embodiment, the first wireless device can transmit an indicationof the first subset of wireless frequencies to the access point. Forexample, after the STA 506E determines it will transmit thecommunication 518 on the channel 526, it can transmit the channelselection to the AP 504, for example in a QoS field and/or a PS-Pollframe. In an embodiment, the first wireless device can transmit anindication of the first set of wireless frequencies to one or moredevices not associated with the access point. For example, withreference to FIG. 2B, after the STA 256A chooses a channel, it canindicate the channel selection to the STA 256G and/or the AP 254C.

In an embodiment, the reference signal can include an indication of adeferral time for third party devices. In an embodiment, the referencesignal can include an indication of devices that are eligible totransmit at a particular time. In an embodiment, the reference signalcan include an indication of a power level at which at least one deviceshould transmit.

In various embodiments, the reference signal can include an indicationof a deferral time for third party devices. In an embodiment, thereference signal can include an indication of devices that are eligibleto transmit at a particular time. In an embodiment, the reference signalcan include an assignment of channels to one or more devices in thesecond subset of wireless devices. For example, the extended payload 750(FIG. 7A) can include one or more channel assignments or transmitauthorizations. In some embodiments, the transmit authorizations caninclude a list of addresses of devices eligible to transmit at aparticular time (for example, the next SIFS time). The transmitauthorizations can include a group identifier defined in advance, forexample, by the AP 504.

In an embodiment, the reference signal can include an indication of apower level at which at least one device should transmit. For example,the extended payload 750 can include an indication of a back-off fromthe STA's 506E nominal transmit power, which the STA 506E can indicateto the AP 504.

In various embodiments, the reference signal can include an indicationof a transmission time of at least one device in the second subset ofwireless devices. In an embodiment, the reference signal can include aclear-to-send frame (CTS). In an embodiment, the reference signal caninclude a clear-to-send frame (CTS) and an extended payload comprisingone or more payload elements. In an embodiment, the reference signal caninclude a clear-to-send frame (CTS) comprising a high-throughput control(HTC) field indicating one or more target devices. In an embodiment, thereference signal can include an aggregated media access control protocoldata unit (A-MPDU) comprising a clear-to-send frame (CTS) and one ormore payload elements. For example, the reference signal can include thereference signal 700, described above with respect to FIG. 7A.

In an embodiment, the first wireless device can schedule a time at whichto transmit communications to the access point. In an embodiment, thefirst wireless device can transmit to the access point an indicationthat the first device can be ready to send data. In an embodiment, thefirst wireless device can transmit to the access point aquality-of-service (QoS) field indicating that the first device can beready to send data. In an embodiment, the first wireless device cantransmit to the access point a power-save poll (PS-Poll) frameindicating that the first device can be ready to send data. For example,the STA 506E can transmit the various messages discussed herein to theAP 504.

In an embodiment, the method shown in FIG. 11 can be implemented in awireless device that can include a receiving circuit, and a transmittingcircuit. Those skilled in the art will appreciate that a wireless devicecan have more components than the simplified wireless device describedherein. The wireless device described herein includes only thosecomponents useful for describing some prominent features ofimplementations within the scope of the claims.

The receiving circuit can be configured to receive the reference signal.In some embodiments, the receiving circuit can be configured to performat least block 1110 of FIG. 11. The receiving circuit can include one ormore of the receiver 412 (FIG. 4), the antenna 416 (FIG. 4), and thetransceiver 414 (FIG. 4). In some implementations, means for receivingcan include the receiving circuit.

The transmitting circuit can be configured to transmit the firstcommunication. In some embodiments, the transmitting circuit can beconfigured to perform at least block 1120 of FIG. 11. The transmittingcircuit can include one or more of the transmitter 410 (FIG. 4), theantenna 416 (FIG. 4), and the transceiver 414 (FIG. 4). In someimplementations, means for transmitting can include the transmittingcircuit.

FIG. 12 shows a flowchart 1200 for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 500 of FIG. 5. The method can be implemented in whole or in partby the devices described herein, such as the wireless device 402 shownin FIG. 4. Although the illustrated method is described herein withreference to the wireless communication system 120 discussed above withrespect to FIG. 1, the wireless communication systems 200, 250, 300, and500 discussed above with respect to FIGS. 2-3 and 5A, and the wirelessdevice 402 discussed above with respect to FIG. 4, a person havingordinary skill in the art will appreciate that the illustrated methodcan be implemented by another device described herein, or any othersuitable device. Although the illustrated method is described hereinwith reference to a particular order, in various embodiments, blocksherein can be performed in a different order, or omitted, and additionalblocks can be added.

First, at block 1210, the access point exchanges at least one protectionframe with at least one of a first and second wireless device. In anembodiment, exchanging at least one protection frame can includereceiving a ready-to-send (RTX) frame from at least one of the first andsecond device. In an embodiment, exchanging at least one protectionframe can include transmitting a reference signal to the first andsecond device. For example, the AP 504 can exchange the RTX 620 and/orthe reference signal CTX 602 (FIG. 6D) with the STAs 506A-506E.

In various embodiments, the reference signal can include an indicationof a deferral time for third party devices. In an embodiment, thereference signal can include an indication of devices that are eligibleto transmit at a particular time. In an embodiment, the reference signalcan include an assignment of channels to one or more devices in thesecond subset of wireless devices. For example, the extended payload 750(FIG. 7A) can include one or more channel assignments or transmitauthorizations. In some embodiments, the transmit authorizations caninclude a list of addresses of devices eligible to transmit at aparticular time (for example, the next SIFS time). The transmitauthorizations can include a group identifier defined in advance, forexample, by the AP 504.

In an embodiment, the reference signal can include an indication of apower level at which at least one device should transmit. For example,the extended payload 750 can include an indication of a back-off fromthe STA's 506E nominal transmit power, which the STA 506E can indicateto the AP 504.

In various embodiments, the reference signal can include an indicationof a transmission time of at least one device in the second subset ofwireless devices. In an embodiment, the reference signal can include aclear-to-send frame (CTS). In an embodiment, the reference signal caninclude a clear-to-send frame (CTS) and an extended payload comprisingone or more payload elements. In an embodiment, the reference signal caninclude a clear-to-send frame (CTS) comprising a high-throughput control(HTC) field indicating one or more target devices. In an embodiment, thereference signal can include an aggregated media access control protocoldata unit (A-MPDU) comprising a clear-to-send frame (CTS) and one ormore payload elements. For example, the reference signal can include thereference signal 700, described above with respect to FIG. 7A.

In an embodiment, the access point can assign the first and/or secondset of wireless frequencies to the first and/or second device,respectively. For example, the AP 504 can assign the channel 526 to theSTA 506E. The AP 504 can assign channels in coordination with otherdevices, based on observed interference, etc. In an embodiment, theaccess point can receive an indication of the first and/or second set ofwireless frequencies from the first and/or second device, respectively.For example, the STA 506E can make its own channel assignment, forexample, based on observed interference. The STA 506E can transmit thechannel assignment to the AP 504.

In an embodiment, the first wireless device can include a legacy deviceincapable simultaneously transmitting on the entire set of wirelessfrequencies available for use by both the first and second wirelessdevice. Returning to FIG. 5A, for example, the STA 506E can be a legacydevice. In some embodiments, the STA 506E can be incapable oftransmitting on the entire first subset of frequencies such as, forexample, where it must transmit on a primary channel.

Then, at block 1220, the access point receives a first communication ona first set of wireless frequencies from the first wireless device. Forexample, the AP 504 can receive the communication 518 from the STA 506Eon the primary channel 526.

Next, at block 1230, the access point receives a second communication,at least partially concurrent with the first communication, on a secondset of wireless frequencies from the second wireless device. The firstset and the second set are mutually exclusive subsets of a set ofwireless frequencies available for use by both the first and secondwireless device. For example, the AP 504 can receive the communication510 from the STA 506A on the channel 524. The frequencies of thechannels 526 and 526 are mutually exclusive.

Thereafter, at block 1240, the access point transmits at least oneacknowledgment of the first and second communication. For example, theAP 504 can transmit the BA 904A (FIG. 9A). In an embodiment, the accesspoint transmits a single broadcast acknowledgment on only the firstsubset of frequencies. For example, the AP 504 can transmit only the BBA904E (FIG. 9C) on the primary channel 526. In an embodiment, the accesspoint receives an acknowledgment request and transmits theacknowledgment in response to the acknowledgment request. For example,the AP 504 can receive a BAR 902B (FIG. 9A) from the STA 506B on thechannel 522, and can respond with the BA 904B on the channel 522.

In some embodiment, the access point can schedule a time at which toreceive communications from the second subset of wireless devices. Inone embodiment, the access point can schedule a time at which to receivecommunications from the second subset of wireless devices and transmit areference signal to at least one device in the second subset of wirelessdevices at the scheduled time. For example, at the scheduled transmittime, the AP 504 can transmit the reference signal 700 to synchronizethe STAs 506A-506E. In one embodiment, the access point can receive,from at least one device in the second subset of wireless devices, anindication that the at least one device can be ready to send data. Forexample, the AP 504 can receive the RTX 620 from the STA 506E (FIG. 6F).

In some embodiments, the access point can receive, from at least onedevice in the second subset of wireless devices, a quality-of-service(QoS) field indicating that the at least one device can be ready to senddata. For example, the STA 506E can transmit a QoS field to the AP 504to indicate that it has data to transmit. In another embodiment, theaccess point can receive, from at least one device in the second subsetof wireless devices, a power-save poll (PS-Poll) frame indicating thatthe at least one device can be ready to send data. For example, the STA506E can transmit the PS-Poll frame to the AP 504 to indicate that ithas data to transmit.

In an embodiment, the method shown in FIG. 12 can be implemented in awireless device that can include an exchanging circuit, a receivingcircuit, and a transmitting circuit. Those skilled in the art willappreciate that a wireless device can have more components than thesimplified wireless device described herein. The wireless devicedescribed herein includes only those components useful for describingsome prominent features of implementations within the scope of theclaims.

The exchanging circuit can be configured to exchange the protectionframe. In some embodiments, the exchanging circuit can be configured toperform at least block 1210 of FIG. 12. The exchanging circuit caninclude one or more of the transmitter 410 (FIG. 4), the receiver 412(FIG. 4), the antenna 416 (FIG. 4), and the transceiver 414 (FIG. 4). Insome implementations, means for exchanging can include the exchangingcircuit.

The receiving circuit can be configured to receive communications fromthe first and second wireless devices. In some embodiments, thereceiving circuit can be configured to perform at least blocks 1220and/or 1230 of FIG. 12. The receiving circuit can include one or more ofthe receiver 412 (FIG. 4), the antenna 416 (FIG. 4), and the transceiver414 (FIG. 4). In some implementations, means for receiving can includethe receiving circuit.

The transmitting circuit can be configured to transmit theacknowledgment. In some embodiments, the transmitting circuit can beconfigured to perform at least block 1240 of FIG. 12. The transmittingcircuit can include one or more of the transmitter 410 (FIG. 4), theantenna 416 (FIG. 4), and the transceiver 414 (FIG. 4). In someimplementations, means for transmitting can include the transmittingcircuit.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (for example, looking upin a table, a database or another data structure), ascertaining and thelike. Also, “determining” may include receiving (for example, receivinginformation), accessing (for example, accessing data in a memory) andthe like. Also, “determining” may include resolving, selecting,choosing, establishing and the like. Further, a “channel width” as usedherein may encompass or may also be referred to as a bandwidth incertain aspects.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above can be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures can be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor can be a microprocessor, but in thealternative, the processor can be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, for example, acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

In one or more aspects, the functions described can be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions can be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media can be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk, and Blu-ray® disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects, computer readable medium may comprisenon-transitory computer readable medium (for example, tangible media).In addition, in some aspects computer readable medium may comprisetransitory computer readable medium (for example, a signal).Combinations of the above should also be included within the scope ofcomputer-readable media.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions can beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions can bemodified without departing from the scope of the claims.

Software or instructions may also be transmitted over a transmissionmedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (for example, RAM, ROM, a physical storagemedium such as a compact disc (CD) or floppy disk, etc.), such that auser terminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations can be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure can be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of high-efficiency wireless frequencydivision multiplexing, comprising: receiving, at a first wireless devicefrom an access point, a reference signal for reserving an entirewireless medium including a set of wireless frequencies available foruse by both the first wireless device and a second wireless device, thereference signal including a received signal strength indicator (RSSI)indication of a power level at which at least one of the first andsecond wireless devices should transmit communications; in response toreceiving the reference signal, transmitting, from the first wirelessdevice to the access point, a first communication on a first subset ofthe set of wireless frequencies, the first communication beingtransmitted at least partially concurrent with a second communicationtransmitted on a second subset of the set of wireless frequencies fromthe second wireless device to the access point, and the first and secondsubsets of the set of wireless frequencies being mutually exclusivesubsets of the set of wireless frequencies; and receiving, from theaccess point on only the first subset of the set of wirelessfrequencies, an acknowledgment of the first communication.
 2. The methodof claim 1, wherein receiving the acknowledgment of the firstcommunication comprises a single broadcast acknowledgment.
 3. The methodof claim 1, further comprising transmitting, from the first wirelessdevice, an acknowledgment request to the access point, wherein theacknowledgment of the first communication is in response to theacknowledgment request.
 4. The method of claim 1, wherein the firstsubset of the set of wireless frequencies is assigned to the firstwireless device and the second subset of the set of wireless frequenciesis assigned to the second wireless device.
 5. The method of claim 1,further comprising transmitting, from the first wireless device to theaccess point, an indication of the first subset of the set of wirelessfrequencies.
 6. The method of claim 1, wherein the first wireless deviceis capable of simultaneously transmitting on both the first subset ofthe set of wireless frequencies and the second subset of the set ofwireless frequencies.
 7. The method of claim 1, further comprisingtransmitting a ready-to-send (RTX) frame from the first wireless deviceto the access point for reserving the entire wireless medium.
 8. Themethod of claim 7, wherein the ready-to-send (RTX) frame comprises oneor more of: a frame control field, a duration field, a source addressfield, a destination address field, and an information payloadcomprising one or more of the following indications: a requestedtransmission time, a size of one or more queues for transmission, aquality-of-service (QoS) indication for a requested transmission, and arequested transmission bandwidth.
 9. The method of claim 7, wherein theready-to-send (RTX) frame includes a high throughput control (HTC) fieldwith an indication reverse decision grant (RDG)=1.
 10. The method ofclaim 1, wherein the reference signal includes a high throughput control(HTC) field with an indication reverse decision grant (RDG)=1.
 11. Themethod of claim 1, wherein the reference signal comprises at least aportion of a power save multi-poll (PSMP) frame, a PSMP-UTT start offsetwithin a station information field identifying a start time for anuplink frequency division multiple access (UL FDMA) transmission, aPSMP-UTT duration identifying a duration of the UL FDMA transmission,and a STA ID field comprising an identifier of stations allowed totransmit.
 12. The method of claim 1, wherein the reference signalcomprises a frame control field, a duration field, a receive addressfield, a transmit address field, a length field, a station informationfield, one or more optional padding bits, and a frame check sequence(FCS).
 13. The method of claim 1, wherein the reference signal comprisesan indication of a deferral time for third party devices.
 14. The methodof claim 1, wherein the reference signal comprises an indication ofdevices that are eligible to transmit at a particular time.
 15. Themethod of claim 1, wherein the reference signal comprises an assignmentof channels to one or more devices included in the first set of wirelessdevices.
 16. The method of claim 1, wherein the reference signalcomprises an indication of a transmission time of at least one deviceincluded in the first set of wireless devices.
 17. The method of claim1, wherein the reference signal comprises a clear-to-send frame (CTS).18. The method of claim 1, wherein the reference signal comprises aclear-to-send frame (CTS) and an extended payload comprising one or morepayload elements.
 19. The method of claim 1, wherein the referencesignal comprises a clear-to-send frame (CTS) comprising ahigh-throughput control (HTC) field indicating one or more targetdevices.
 20. The method of claim 1, wherein the reference signalcomprises an aggregated media access control protocol data unit (A-MPDU)comprising a clear-to-send frame (CTS) and one or more payload elements.21. The method of claim 1, further comprising scheduling, in connectionwith the access point, a time at which to transmit communications, fromthe first wireless device, to the access point.
 22. The method of claim21, further comprising receiving, at the first wireless device, thereference signal at the scheduled time.
 23. The method of claim 1,further comprising transmitting, to the access point, an indication thatthe first wireless device is ready to send data.
 24. The method of claim23, wherein the indication comprises a quality-of-service (QoS) field.25. The method of claim 23, wherein the indication comprises apower-save poll (PS-Poll) frame.
 26. An apparatus configured to performhigh-efficiency wireless frequency division multiplexing, comprising: aprocessor; a receiver, in connection with the processor and configuredto receive, at the apparatus from an access point, a reference signalfor reserving an entire wireless medium including a set of wirelessfrequencies available for use by both the apparatus and a wirelessdevice, the reference signal including a received signal strengthindicator (RSSI) indication of a power level at which at least one ofthe apparatus and the wireless device should transmit communications;and a transmitter, in connection with the processor and configured to,in response to receiving the reference signal, transmit, from theapparatus to the access point, a first communication on a first subsetof the set of wireless frequencies, the first communication beingtransmitted at least partially concurrent with a second communicationtransmitted on a second subset of the set of wireless frequencies fromthe wireless device to the access point, and the first and secondsubsets of the set of wireless frequencies being mutually exclusivesubsets of the set of wireless frequencies, the receiver being furtherconfigured to receive, from the access point on only the first subset ofthe set of wireless frequencies, an acknowledgment of the firstcommunication.
 27. The apparatus of claim 26, wherein the acknowledgmentof the first communication comprises a single broadcast acknowledgment.28. The apparatus of claim 26, wherein the transmitter is furtherconfigured to transmit, from the first wireless device, anacknowledgment request to the access point, wherein the acknowledgmentof the first communication is in response to the acknowledgment request.29. The apparatus of claim 26, wherein the first subset of the set ofwireless frequencies is assigned to the apparatus and the second subsetof the set of wireless frequencies is assigned to the wireless device.30. The apparatus of claim 26, wherein the transmitter is furtherconfigured to transmit, from the first wireless device to the accesspoint, an indication of the first subset of the set of wirelessfrequencies.
 31. The apparatus of claim 26, wherein the apparatus iscapable of simultaneously transmitting on both the first subset of theset of wireless frequencies and the second subset of the set of wirelessfrequencies.
 32. The apparatus of claim 26, wherein wherein thetransmitter is further configured to transmit a ready-to-send (RTX)frame from the apparatus to the access point for reserving the entirewireless medium.
 33. The apparatus of claim 32, wherein theready-to-send (RTX) frame comprises one or more of: a frame controlfield, a duration field, a source address field, a destination addressfield, and an information payload comprising one or more of thefollowing indications: a requested transmission time, a size of one ormore queues for transmission, a quality-of-service (QoS) indication fora requested transmission, and a requested transmission bandwidth. 34.The apparatus of claim 32, wherein the ready-to-send (RTX) frameinclude's a high throughput control (HTC) field with an indicationreverse decision grant (RDG)=1.
 35. The apparatus of claim 26, whereinthe reference signal includes a high throughput control (HTC) field withan indication reverse decision grant (RDG)=1.
 36. The apparatus of claim26, wherein the reference signal comprises at least a portion of a powersave multi-poll (PSMP) frame, a PSMP-UTT start offset within a stationinformation field identifying a start time for an uplink frequencydivision multiple access (UL FDMA) transmission, a PSMP-UTT durationidentifying a duration of the UL FDMA transmission, and a STA ID fieldcomprising an identifier of stations allowed to transmit.
 37. Theapparatus of claim 26, wherein the reference signal comprises a framecontrol field, a duration field, a receive address field, a transmitaddress field, a length field, a station information field, one or moreoptional padding bits, and a frame check sequence (FCS).
 38. Theapparatus of claim 26, wherein the reference signal comprises anindication of a deferral time for third party devices.
 39. The apparatusof claim 26, wherein the reference signal comprises an indication ofdevices that are eligible to transmit at a particular time.
 40. Theapparatus of claim 26, wherein the reference signal comprises anassignment of channels to one or more devices included in the first setof wireless devices.
 41. The apparatus of claim 26, wherein thereference signal comprises an indication of a transmission time of atleast one device included in the first set of wireless devices.
 42. Theapparatus of claim 26, wherein the reference signal comprises aclear-to-send frame (CTS).
 43. The apparatus of claim 26, wherein thereference signal comprises a clear-to-send frame (CTS) and an extendedpayload comprising one or more payload elements.
 44. The apparatus ofclaim 26, wherein the reference signal comprises a clear-to-send frame(CTS) comprising a high-throughput control (HTC) field indicating one ormore target devices.
 45. The apparatus of claim 26, wherein thereference signal comprises an aggregated media access control protocoldata unit (A-MPDU) comprising a clear-to-send frame (CTS) and one ormore payload elements.
 46. The apparatus of claim 26, wherein theprocessor is configured to schedule, in connection with the accesspoint, a time at which to transmit communications, from the apparatus,to the access point.
 47. The apparatus of claim 46, wherein the receiveris further configured to receive the reference signal at the scheduledtime.
 48. The apparatus of claim 26, wherein the transmitter is furtherconfigured to transmit, to the access point, an indication that theapparatus is ready to send data.
 49. The apparatus of claim 48, whereinthe indication comprises a quality-of-service (QoS) field.
 50. Theapparatus of claim 48, wherein the indication comprises a power-savepoll (PS-Poll) frame.
 51. An apparatus for high-efficiency wirelessfrequency division multiplexing, comprising: means for receiving, at theapparatus from an access point, a reference signal for reserving anentire wireless medium including a set of wireless frequencies availablefor use by both the apparatus and a wireless device, the referencesignal including a received signal strength indicator (RSSI) indicationof a power level at which at least one of the apparatus and the wirelessdevice should transmit communications; means for, in response toreceiving the reference signal, transmitting, from the apparatus to theaccess point, a first communication on a first subset of the set ofwireless frequencies, the first communication being transmitted at leastpartially concurrent with a second communication transmitted on a secondsubset of the set of wireless frequencies from the wireless device tothe access point, and the first and second subsets of the set ofwireless frequencies being mutually exclusive subsets of the set ofwireless frequencies; and means for receiving, from the access point ononly the first subset of the set of wireless frequencies, anacknowledgment of the first communication.
 52. A non-transitorycomputer-readable medium comprising code that, when executed, causes anapparatus to: receive, at the apparatus from an access point, areference signal for reserving an entire wireless medium including a setof wireless frequencies available for use by both the apparatus and awireless device, the reference signal including a received signalstrength indicator (RSSI) indication of a power level at which at leastone of the apparatus and the wireless device should transmitcommunications; in response to receiving the reference signal, transmit,from the apparatus to the access point, a first communication on a firstsubset of the set of wireless frequencies, the first communication beingtransmitted at least partially concurrent with a second communicationtransmitted on a second subset of the set of wireless frequencies fromthe wireless device to the access point, and the first and secondsubsets of the set of wireless frequencies being mutually exclusivesubsets of the set of wireless frequencies; and receive, from the accesspoint on only the first subset of the set of wireless frequencies, anacknowledgment of the first communication.